Medical treatment system and methods using a plurality of fluid lines

ABSTRACT

A medical treatment system, such as peritoneal dialysis system, may include control and other features to enhance patient comfort and ease of use. For example, a peritoneal dialysis system may include a control system that can adjust the volume of fluid infused into the peritoneal cavity to prevent the intraperitoneal fluid volume from exceeding a pre-determined amount. The control system can adjust by adding one or more therapy cycles, allowing for fill volumes during each cycle to be reduced. The control system may continue to allow the fluid to drain from the peritoneal cavity as completely as possible before starting the next therapy cycle. The control system may also adjust the dwell time of fluid within the peritoneal cavity during therapy cycles in order to complete a therapy within a scheduled time period. The cycler may also be configured to have a heater control system that monitors both the temperature of a heating tray and the temperature of a bag of dialysis fluid in order to bring the temperature of the dialysis fluid rapidly to a specified temperature, with minimal temperature overshoot.

This application is a division of U.S. patent application Ser. No.15/432,265, filed Feb. 14, 2017, now U.S. Pat. No. 9,981,079, which is adivision of U.S. patent application Ser. No. 13/667,679, filed Nov. 2,2012, now U.S. Pat. No. 9,861,732, which claims the benefit of U.S.Provisional Application No. 61/555,926, filed Nov. 4, 2011, all of whichare hereby incorporated by reference in their entireties.

BACKGROUND

Peritoneal Dialysis (PD) involves the periodic infusion of sterileaqueous solution (called peritoneal dialysis solution, or dialysate)into the peritoneal cavity of a patient. Diffusion and osmosis exchangestake place between the solution and the bloodstream across the naturalbody membranes. These exchanges transfer waste products to the dialysatethat the kidneys normally excrete. The waste products typically consistof solutes like sodium and chloride ions, and other compounds normallyexcreted through the kidneys like urea, creatinine, and water. Thediffusion of water across the peritoneal membrane during dialysis iscalled ultrafiltration.

Conventional peritoneal dialysis solutions include dextrose inconcentrations sufficient to generate the necessary osmotic pressure toremove water from the patient through ultrafiltration.

Continuous Ambulatory Peritoneal Dialysis (CAPD) is a popular form ofPD. A patient performs CAPD manually about four times a day. During adrain/fill procedure for CAPD, the patient initially drains spentperitoneal dialysis solution from his/her peritoneal cavity, and theninfuses fresh peritoneal dialysis solution into his/her peritonealcavity. This drain and fill procedure usually takes about 1 hour.

Automated Peritoneal Dialysis (APD) is another popular form of PD. APDuses a machine, called a cycler, to automatically infuse, dwell, anddrain peritoneal dialysis solution to and from the patient's peritonealcavity. APD is particularly attractive to a PD patient, because it canbe performed at night while the patient is asleep. This frees thepatient from the day-to-day demands of CAPD during his/her waking andworking hours.

The APD sequence typically lasts for several hours. It often begins withan initial drain phase to empty the peritoneal cavity of spentdialysate. The APD sequence then proceeds through a succession of fill,dwell, and drain phases that follow one after the other. Eachfill/dwell/drain sequence is called a cycle.

During the fill phase, the cycler transfers a predetermined volume offresh, warmed dialysate into the peritoneal cavity of the patient. Thedialysate remains (or “dwells”) within the peritoneal cavity for aperiod of time. This is called the dwell phase. During the drain phase,the cycler removes the spent dialysate from the peritoneal cavity.

The number of fill/dwell/drain cycles that are required during a givenAPD session depends upon the total volume of dialysate prescribed forthe patient's APD regimen, and is either entered as part of thetreatment prescription or calculated by the cycler.

APD can be and is practiced in different ways.

Continuous Cycling Peritoneal Dialysis (CCPD) is one commonly used APDmodality. During each fill/dwell/drain phase of CCPD, the cycler infusesa prescribed volume of dialysate. After a prescribed dwell period, thecycler completely drains this liquid volume from the patient, leavingthe peritoneal cavity empty, or “dry.” Typically, CCPD employs 4-8fill/dwell/drain cycles to achieve a prescribed therapy volume.

After the last prescribed fill/dwell/drain cycle in CCPD, the cyclerinfuses a final fill volume. The final fill volume dwells in the patientfor an extended period of time. It is drained either at the onset of thenext CCPD session in the evening, or during a mid-day exchange. Thefinal fill volume can contain a different concentration of dextrose thanthe fill volume of the successive CCPD fill/dwell/drain fill cycles thecycler provides.

Intermittent Peritoneal Dialysis (IPD) is another APD modality. IPD istypically used in acute situations, when a patient suddenly entersdialysis therapy. IPD can also be used when a patient requires PD, butcannot undertake the responsibilities of CAPD or otherwise do it athome.

Like CCPD, IPD involves a series of fill/dwell/drain cycles. UnlikeCCPD, IPD does not include a final fill phase. In IPD, the patient'speritoneal cavity is left free of dialysate (or “dry”) in between APDtherapy sessions.

Tidal Peritoneal Dialysis (TPD) is another APD modality. Like CCPD, TPDincludes a series of fill/dwell/drain cycles. Unlike CCPD, TPD does notcompletely drain dialysate from the peritoneal cavity during each drainphase. Instead, TPD establishes a base volume during the first fillphase and drains only a portion of this volume during the first drainphase. Subsequent fill/dwell/drain cycles infuse and then drain areplacement volume on top of the base volume. The last drain phaseremoves all dialysate from the peritoneal cavity.

There is a variation of TPD that includes cycles during which thepatient is completely drained and infused with a new full base volume ofdialysis.

TPD can include a final fill cycle, like CCPD. Alternatively, TPD canavoid the final fill cycle, like IPD.

APD offers flexibility and quality of life enhancements to a personrequiring dialysis. APD can free the patient from the fatigue andinconvenience that the day to day practice of CAPD represents to someindividuals. APD can give back to the patient his or her waking andworking hours free of the need to conduct dialysis exchanges.

Still, the complexity and size of past machines and associateddisposables for various APD modalities have dampened widespread patientacceptance of APD as an alternative to manual peritoneal dialysismethods.

SUMMARY OF INVENTION

Aspects of the invention relate to various components, systems andmethods for use in medical applications, including medical infusionoperations such as peritoneal dialysis. In some cases, aspects of theinvention are limited to applications in peritoneal dialysis, whileothers to more general dialysis applications (e.g., hemodialysis) orinfusion applications, while others to more general methods orprocesses. Thus, aspects of the invention are not necessarily limited toAPD systems and methods, although many of the illustrative embodimentsdescribed relate to APD.

In one aspect of the invention, a tubing state detector may be includedwith a dialysis system for detecting the presence or absence of a tubingsegment, such as a portion of a patient line to be connected to apatient access for delivering dialysate to the peritoneal cavity. Thetubing state detector may include a first light emitter having a firstoptical axis directed toward a space in which a tubing segment is to bepositioned, and a second light emitter, adjacent to the first lightemitter and having a second optical axis directed toward the space. Anoptical sensor may be positioned on a side of the space opposite thefirst and second light emitters and arranged to receive light emitted bythe first and second light emitters to determine a presence or absenceof a tubing segment in the space.

In one embodiment, the first optical axis may be approximately collinearwith a sensor optical axis of the optical sensor, and may passapproximately through a center of a tubing segment when the tubingsegment is positioned in the space. In contrast, the second optical axismay be approximately parallel to the first optical axis, and thus, thesecond optical axis may be offset from the center of the tubing segmentand sensor optical axis.

The optical sensor may be arranged to detect a range of light levelswhen a tubing segment is in the space, e.g., a light level that ishigher and/or lower that a light level detected when the tubing segmentis absent from the space. However, the optical sensor may detect a lowerlight level from the second light emitter when a tubing segment is inthe space that is detected when the tubing segment it absent from thespace. For example, with a tubing segment in the space, a detected lightlevel for both the first and second light emitters may be within about15-20% of a calibration light level for the first and second lightemitters, where the calibration light level is a level detected when atubing segment is known to be absent from the space. However, with atubing segment not in the space, a detected light level for the secondlight emitter may be less than about 15-20% of the calibration lightlevel for the second light emitter. This lower light level detection maybe used to determine that a tubing segment is in the space.

In another embodiment, the tubing state detector may be arranged todetect whether there is liquid present in the tubing segment, e.g.,whether the patient line is properly primed for use. For example, thedetector may include a third light emitter having a third optical axisthat is arranged at an oblique angle relative to the sensor opticalaxis. The oblique angle may be between 90 and 180 degrees, e.g., about110-120 degrees. The optical sensor and third light emitter may bearranged such that with a tubing segment in the space and the tubingsegment containing no liquid, a light level detected by the opticalsensor may be over about 150% of a calibration light level detected withno tubing segment in the space. In addition, with a tubing segment inthe space and containing liquid, the optical sensor may detect a lightlevel from the third light emitter that is less than about 125% of thecalibration light level. Thus, the optical sensor and third lightemitter may be arranged such that with a tubing segment in the space andthe tubing segment containing no liquid, a light level detected by theoptical sensor may be over a threshold level, and with a tubing segmentin the space and the tubing segment containing liquid, a light leveldetected by the optical sensor is less than the threshold level. Thisarrangement may allow the detector to determine whether liquid iscontained in the patient line, e.g., whether the patient line isproperly primed. In one embodiment, the third light emitter and theoptical sensor may be arranged such that the optical sensor receiveslight from the third light emitter both when a tubing segment in thespace is filled with liquid and when a tubing segment in the space isempty of liquid. Thus, the presence or absence of liquid in the tubingsegment may be determined based on a detected light intensity ratherthan the presence or absence of light. This may help the system avoidfalse condition detection that might result if the detector were to usethe absence of detected light to indicate a condition, such as thepresence of liquid in the tubing segment. That is, since the opticalsensor detects light from the third light emitter regardless of thepresence of liquid, the optical sensor may be able to determine whetherthe third light emitter is operating properly (or at all). The space inwhich the tubing segment is held may be arranged to receive and hold thetubing segment, which may have a cylindrical outer surface, withoutsubstantially deforming the tubing segment. Thus, the detector mayoperate without deforming the tubing segment, thereby avoiding potentialproblems such as pinching, reduced flow in the tubing segment, etc.

In another aspect of the invention, a tubing state detector fordetecting whether liquid is contained in a tubing segment may include afill state light emitter having an optical axis that is arranged to passthrough a space in which a tubing segment is to be positioned. The spacemay be arranged to receive a tubing segment having a cylindrical outersurface and to hold the tubing segment without substantially deformingthe tubing segment. Thus, the detector may be useable with common tubingfrequently used in dialysis systems and without requiring specialpurpose fittings or other components. An optical sensor may bepositioned on a side of the space opposite the fill state light emitterand arranged to receive light emitted by the fill state light emitter todetermine a presence or absence of liquid in the tubing segment. In oneembodiment, the optical sensor may have a sensor optical axis that isarranged at an oblique angle to the optical axis of the fill state lightemitter, and may be arranged to detect whether liquid is present in thetubing segment or not. The oblique angle may be between 90 and 180degrees, e.g., about 110-120 degrees, and the optical sensor may bearranged to receive light from the fill state light emitter whetherthere is liquid present in the tubing segment or not.

The optical sensor and fill state light emitter may be arranged suchthat with a tubing segment in the space and the tubing segmentcontaining no liquid, a light level detected by the optical sensor isover a threshold level, and such that with a tubing segment in the spaceand the tubing segment containing liquid, a light level detected by theoptical sensor is less than the threshold level. Thus, if the opticalsensor detects a light level below a threshold, e.g., below about125-150% of a light level detected with no tubing segment in the space,a determination may be made that the tubing segment is filled withliquid. The fill state light emitter (as with other light emitters) maybe a light emitting diode or other electromagnetic radiation emittingcomponent, such as a device that emits infrared, UV, visible light, orother light in the visible and/or invisible spectrum.

In one embodiment, the tubing state detector may include a first lightemitter having a first optical axis directed toward the space, and asecond light emitter having a second optical axis directed toward thespace. The second light emitter may be adjacent the first light emitter,and the second optical axis may be parallel to the first optical axis.The optical sensor may be positioned on a side of the space opposite thefirst and second light emitters and arranged to receive light emitted bythe first and second light emitters to determine a presence or absenceof a tubing segment in the space. For example, the first and secondlight emitters may be arranged with respect to each other and theoptical sensor as described above, e.g., the first optical axis may passthrough a center of a tubing segment in the space, the second opticalaxis may be offset from the tubing segment center, etc.

In another aspect of the invention, a peritoneal dialysis system mayinclude at least one pump arranged to pump dialysate for delivery to aperitoneal cavity of a patient, and a patient line fluidly coupled tothe at least one pump such that dialysate delivered from the pump isdirected to the patient line. The patient line may have a distal endarranged for connection to a patient, e.g., for connection to a patientaccess to deliver dialysate to a peritoneal cavity of the patient. Apatient line state detector may be arranged to be associated with thepatient line and to detect both a presence of the patient line and apriming condition of the patient line. For example, the patient linestate detector may be arranged to receive the distal end of the patientline to detect the presence of the distal end and whether the distal endof the patient line is filled with fluid. This arrangement may be usefulto allow the system and a patient to confirm that the patient line issufficiently full of dialysate before connecting the patient line to thepatient access connection.

The patient line state detector may include a cavity to receive thedistal end of the patient line, one or more light emitters associatedwith the cavity arranged to direct light into the cavity, and one ormore light detectors arranged to detect light emitted by the one or morelight emitters. In one embodiment, a single light detector may be usedto determine both the presence or absence of the patient line, as wellas whether liquid is present in the patient line. The patient line statedetector may be arranged in any of the ways that the tubing statedetectors described above may be arranged. For example, first and secondlight emitters may be arranged adjacent each other and on a side of acavity to receive the patient line that is opposite an optical sensor. Athird light emitter may be arranged to have its optical axis arranged atan oblique angle to a sensor axis of the optical sensor, and therebyenable detection of liquid in the patient line. Other features of thetubing state detectors described above may be incorporated into thepatient line state detector, including the detection and use of relativelight levels to indicate a presence of the patient line and/or liquid inthe patient line, and so on.

In another aspect of the invention, a method for detecting a presence ofa tubing segment includes emitting first light along a first opticalaxis toward a space in which a tubing segment is to be optionallypositioned, and emitting second light along a second optical axis towardthe space, wherein the first and second light are emitted from a firstside of the space. At least portions of the first and second light maybe sensed on a second side of the space opposite the first side, and apresence or absence of a tubing segment in the space may be determinedbased on the sensed portions of the first and second light. The secondoptical axis may be approximately parallel to the first optical axis,and the first optical axis may pass through a center of the tubingsegment. In one embodiment, a first calibration level of the first lightmay be detected with no tubing segment in the space, and a first lightlevel may be detected of the first light when a tubing segment is in thespace. The first light level may be higher, or lower, than the firstcalibration level. However, a second calibration level of the secondlight may be detected with no tubing segment in the space, and a secondlight level may be detected of the second light when a tubing segment isin the space, where the second light level is lower than the secondcalibration level. Thus, the detection of a second light level that islower than the second calibration level may indicate the presence of atubing segment in the space. In one embodiment, a detected second lightlevel for the second light may be less than about 15-20% of the secondcalibration level with a tubing segment in the space.

In another aspect of the invention, a method for detecting a presence ofliquid in a tubing segment may include emitting light along an opticalaxis toward a space in which a tubing segment is positioned, where thetubing segment has a cylindrical outer surface, and sensing light alonga sensor optical axis that extends into the space, where the sensoroptical axis is arranged at an oblique angle (e.g., about 110-120degrees) relative to the optical axis. A presence or absence of liquidin the tubing segment in the space may be determined based on a sensedlight level sensed along the sensor optical axis. For example, adetermination may be made that fluid is not present in the tubingsegment if a light level detected along the sensor optical axis is overa threshold level, and a determination may be made that fluid is presentin the tubing segment if a light level detected along the sensor opticalaxis is below a threshold level. The threshold level may beapproximately equal to about 125-150% of a light level detected alongthe sensor optical axis with no tubing segment in the space.

In one aspect of the invention, a disposable fluid handling cassette,such as that useable with an APD cycler device or other infusionapparatus, includes a generally planar body having at least one pumpchamber formed as a depression in a first side of the body and aplurality of flowpaths for fluid that includes a channel. A patient lineport may be arranged for connection to a patient line and be in fluidcommunication with the at least one pump chamber via at least oneflowpath, and a membrane may be attached to the first side of the bodyover the at least one pump chamber. In one embodiment, the membrane mayhave a pump chamber portion with an unstressed shape that generallyconforms to the pump chamber depression in the body and is arranged tobe movable for movement of fluid in the useable space of the pumpchamber. If the cassette body include two or more pump chamberdepressions, the membrane may likewise include two or more pre-shapedpump portions. In other embodiments, the membrane need not be includedwith the cassette, e.g., where a control surface of the cycler interactswith the cassette to control pumping and/or valve functions.

In another embodiment, the pump chamber may include one or more spacerelements that extend from an inner wall of the depression, e.g., to helpprevent the membrane from contacting the inner wall, thereby preventingblocking of an inlet/outlet of the pump chamber, helping remove or trapair in the pump chamber, and/or preventing sticking of the membrane tothe inner wall. The spacer elements may be arranged to minimizedeformation of the membrane at edges of the spacer elements when themembrane is forced against the spacer elements.

In another embodiment, a patient line port and a drain line port may belocated at a first end of the body and be in fluid communication withthe at least one pump chamber via at least one flowpath. A plurality ofsolution line spikes may, on the other hand, be located at a second endof the body opposite the first end, with each of the solution linespikes being in fluid communication with the at least one pump chambervia at least one flowpath. This arrangement may enable automatedconnection of solution lines to the cassette, and/or separate occlusionof the patient and/or drain lines relative to the solution lines. In oneembodiment, a heater bag line port may also be located at the first endof the body and be in fluid communication with the at least one pumpchamber via at least one flowpath. Flexible patient, drain and heaterbag lines may be respectively connected to the patient line port, drainline port and heater bag line port.

In another embodiment, the body may include a vacuum vent clearancedepression formed adjacent the at least one pump chamber. Thisdepression may aid in the removal of fluid (gas and/or liquid) betweenthe membrane and a corresponding control surface of the cycler, e.g., byway of a vacuum port in the control surface. That is, the depression mayhelp ensure that the membrane is not forced against the vacuum port,leaving the port open to draw fluid into a collection chamber asnecessary.

In one embodiment, one or more ports, such as a drain line port andheater bag line port, and/or one or more solution line spikes maycommunicate with a common flowpath channel of the cassette base. Asneeded, a plurality of valves may each be arranged to control flow in arespective flowpath between the at least one pump chamber and thepatient line port, the drain line port, and the plurality of solutionline spikes. In one embodiment, portions of the membrane may bepositioned over respective valves and be movable to open and close therespective valve. Similarly, flow through openings into the pumpchamber(s) may be controlled by corresponding valves that are opened andclosed by movement of one or more portions of the membrane.

In some embodiments, the membrane may close at least some of theflowpaths of the body. That is, the body may be formed with open flowchannels that are closed on at least one side by the membrane. In oneembodiment, the body may include flowpaths formed on opposite planarsides, and at least some of the flowpaths on a first side maycommunicate with flowpaths on the second side.

In one embodiment, one or more spikes on the cassette (e.g., forreceiving dialysate solution) may be covered by a spike cap that sealsthe spike closed and is removable.

In another aspect of the invention, a disposable fluid handlingcassette, for use with a reusable automated peritoneal dialysis cyclerdevice, includes a generally planar body having at least one pumpchamber formed as a depression in a first side of the body and aplurality of flowpaths for fluid that includes a channel, a patient lineport arranged for connection to a patient line, the patient line portbeing in fluid communication with the at least one pump chamber via atleast one flowpath, and a flexible membrane attached to the first sideof the body over the at least one pump chamber. A pump chamber portionof the membrane over the at least one pump chamber may have anunstressed shape that generally conforms to usable area of the pumpchamber depression in the body and be arranged to be movable formovement of fluid in the pump chamber. In one embodiment, the cassetteis configured for operative engagement with a reusable automatedperitoneal dialysis cycler device.

The cassette may include a drain line port arranged for connection to adrain line, the drain line port being in fluid communication with the atleast one pump chamber via at least one flowpath, and/or a plurality ofsolution line spikes that are in fluid communication with the at leastone pump chamber via at least one flowpath. The pump chamber portion ofthe membrane may be generally dome shaped, and may include two pumpchamber portions that have a shape that generally conforms to usablearea of a corresponding pump chamber depression. In one embodiment, avolume of the pump chamber portion may be between 85-110% of the useablevolume of the pump chamber depression. In another embodiment, the pumpchamber portion may be arranged to be 85-110% of the depth of theuseable area of the pump chamber depression. In another embodiment, thepump chamber portion may be arranged to have a size that is between85-100% of the circumference of the useable area of the pump chamberdepression. The useable area of the pump chamber may be defined at leastin part by one or more spacer elements that extend from an inner wall ofthe depression. In one embodiment, a plurality of spacer elements may beof graduated lengths or varying height that define a generallydome-shaped region or other shape. The spacer elements may be arrangedin a concentric elliptical pattern or other shape when viewed in plan.One or more breaks in the pattern may be provided, e.g., to allowcommunication between voids. In one embodiment, the spacer elements maybe arranged to minimize deformation of the membrane at edges of thespacer elements when the membrane is forced against the spacer elements.In another embodiment, one or more spacers may be configured to inhibitthe membrane from covering the fluid inlet and/or outlet of the pumpchamber.

In another aspect of the invention, a fluid handling cassette for usewith a fluid handling system of a medical infusion device includes agenerally planar body having at least one pump chamber formed as adepression in a first side of the body and a plurality of flowpaths forfluid that includes a channel, the at least one pump chamber includingone or more spacer elements that extend from an inner wall of thedepression, a patient line port arranged for connection to a patientline, the patient line port being in fluid communication with the atleast one pump chamber via at least one flowpath, a drain line portarranged for connection to a drain line, the drain line port being influid communication with the at least one pump chamber via at least oneflowpath, and a plurality of solution line spikes being in fluidcommunication with the at least one pump chamber via at least oneflowpath.

In one aspect of the invention, a disposable component system for usewith a fluid line connection system of a peritoneal dialysis systemincludes a fluid handling cassette having a generally planar body withat least one pump chamber formed as a depression in a first side of thebody and a plurality of flowpaths for fluid, a solution line spikelocated at a first end of the body, the solution line spike being influid communication with the at least one pump chamber via at least oneflowpath, and a spike cap configured to removably cover the solutionline spike, wherein the cap includes at least one raised feature (e.g.,an asymmetrical or symmetrical flange) to aid in removal of the cap forconnection to a solution line prior to the commencement of a peritonealdialysis therapy.

In one embodiment, the cassette includes a skirt arranged around thespike to receive the end of the spike cap, and there may be a recessbetween the skirt and the spike that are arranged to aid in forming aseal between the spike cap and skirt.

In another embodiment, a solution line cap may be removably connected toa solution line, and the solution line cap may include a recessedfeature (such as a symmetrical or asymmetrical groove). At least aportion of the solution line cap may include a flexible material, suchas silicone rubber. The recessed feature may aid in the removal of aspike cap from the cassette.

In another embodiment, the spike cap includes a second raised featurethat may function as a stop for the solution line cap.

In another embodiment, a main axis of one or more spikes is insubstantially a same plane as the generally planar body of the fluidhandling cassette.

In another aspect of the invention, a fluid handling cassette for usewith a peritoneal dialysis system includes a generally planar body withat least one pump chamber formed as a depression in a first side of thebody and a plurality of flowpaths for fluid, and a spike located at afirst end of the body for engagement with a dialysate solution line. Thespike may be in fluid communication with the at least one pump chambervia at least one flowpath and include a distal tip and a lumen arrangedso that the distal tip of the spike is positioned substantially near thelongitudinal axis of the spike. In one embodiment, the lumen may bepositioned substantially off the longitudinal axis.

In another aspect of the invention, a disposable component system foruse with a fluid line connection system of a peritoneal dialysis systemincludes a spike cap configured to removably cover a spike of a fluidhandling cassette. The cap may include at least one feature to aid inremoval of the cap for connection to a solution line prior to thecommencement of a peritoneal dialysis therapy. The feature may be araised feature, or a recessed feature, and may be configured forengagement with a solution line cap.

In another aspect of the invention, a disposable component system foruse with a fluid line connection system of a peritoneal dialysis systemincludes a solution line cap for removable attachment to a solutionline, wherein the solution line cap includes at least one feature to aidin removal of a spike cap to enable connection between a solution lineand a spike prior to the commencement of a peritoneal dialysis therapy.The feature may be a raised feature, or a recessed feature, and may beconfigured for engagement with a spike cap. Indicia may e associatedwith a solution line, e.g., so that a solution associated with the linemay be identified and affect at least one function of the peritonealdialysis system.

In another aspect of the invention, a medical infusion fluid handlingsystem, such as an APD system, may be arranged to de-cap and connect oneor more lines (such as solution lines) with one or more spikes or otherconnection ports on a fluid handling cassette. This feature may provideadvantages, such as a reduced likelihood of contamination since no humaninteraction is required to de-cap and connect the lines and spikes. Forexample, an APD system may include a carriage arranged to receive aplurality of solution lines each having a connector end and a cap. Thecarriage may be arranged to move along a first direction so as to movethe connector ends of the solution lines along the first direction, anda cap stripper may be arranged to engage with caps on the solution lineson the carriage. The cap stripper may be arranged to move in a seconddirection transverse to the first direction, as well as to move with thecarriage along the first direction. For example, the carriage may movetoward a cassette in an APD cycler in a first direction so as to engagecaps on the solution lines with caps on spikes of the cassette. The capstripper may engage the caps (e.g., by moving in a direction transverseto the motion of the carriage) and then move with the carriage as thecarriage pulls away from the cassette to remove the caps from thespikes. The carriage may then pull the connector ends of the solutionlines from the caps on the cap stripper, which may retract to allow thecarriage to engage the now exposed solution line connector ends with theexposed spikes on the cassette.

In one embodiment, the carriage may include a plurality of grooves thateach receive a corresponding solution line. By positioning solutionlines in corresponding grooves, each of the lines may be more easilyindividually identified, e.g., by reading a barcode or other identifieron the line, and controlling the system accordingly. The carriage may bemounted to a door of a cycler housing, and a carriage drive may move thecarriage along the first direction. In one embodiment, the carriagedrive may engage the carriage when the door is moved to a closedposition, and disengage from the carriage when the door is moved to anopen position.

In one embodiment, the cap stripper may include a plurality offork-shaped elements arranged to engage with a corresponding cap on asolution line carried by the carriage. The fork-shaped elements may holdthe caps when they are removed from the solution lines, and each of thesolution line caps may itself hold a spike cap. In another embodiment,the cap stripper may include a plurality of rocker arms each associatedwith a fork-shaped element. Each of the rocker arms may be arranged tomove to engage a spike cap, e.g., to assist in removing the spike capfrom the corresponding spike. Each of the rocker arms may be arranged toengage with a corresponding spike cap only when the associatedfork-shaped element engages with a cap on a solution line. Thus, the capstripper may not engage or remove spike caps from the cassette inlocations where there is no corresponding solution line to connect withthe spike.

In another aspect of the invention, a method for connecting fluid linesin a medical infusion fluid handling system, such as an APD cycler, mayinvolve locating solution lines and spikes of a cassette in an enclosedspace away from human touch. The solution lines and/or spikes may havecaps removed and the lines connected to spikes while in the enclosedspace, thus providing the connection while minimizing potentialcontamination at the connection, e.g., by fingers carrying pathogens orother potentially harmful substances. For example, one method inaccordance with this aspect of the invention includes providing aplurality of solution lines each having a connector end and a cap,providing a fluid handling cassette having a plurality of spikes eachcovered by a spike cap, enclosing the connector ends of the plurality ofsolution lines with caps covering the connector ends and the pluralityof spikes with spike caps covering the spikes in a space that preventshuman touch of the caps or spike caps, removing the caps from theconnector ends of the plurality of solution lines without removing thecaps or connector ends from the space, removing the spike caps from thespikes without removing the spike caps or spikes from the space,engaging the caps with respective ones of the spike caps, and fluidlyconnecting the plurality of connector ends to corresponding spikes whilemaintaining the connector ends and spikes in the space and protectedfrom human touch.

In one embodiment, the solution line caps and spike caps may be engagedwith each other before their removal from the lines or spikes, and thenmay be removed from both the lines and the spikes while engaged witheach other. This technique may simplify the de-capping/capping process,as well as allow for easier storage of the caps.

In another embodiment, the solution lines may be disconnected from thespikes, and the connector ends of the lines and the spikes may bere-capped, e.g., after a treatment is completed.

In another aspect of the invention, a dialysis machine may include afluid handling cassette having a plurality of spikes and a plurality ofspike caps covering a respective spike, a plurality of solution lineseach having a cap covering a connector end of the respective line, and acap stripper arranged to remove one or more caps from a connector end ofa solution line, and remove one or more spike caps from a spike on thecassette while the one or more caps are secured to a corresponding oneof the spike caps. As discussed above, the machine may be arranged toautomatically fluidly connect a connector end of a solution line with acorresponding spike after the caps are removed.

In another aspect of the invention, a dialysis machine, such as an APDsystem, may include a cassette having a plurality of fluid spikes and aplurality of spike caps covering a respective spike, a carriage arrangedto receive a plurality of solution lines each having a cap covering aconnector end of the respective line, and a cap stripper arranged toengage one or more caps covering a connector end of a line. The carriageand cap stripper may be configured to engage one or more caps on aconnector end of a line while the one or more caps are engaged with acorresponding spike cap covering a spike on the cassette, and to removethe spike cap from the spike and the cap from the connector end of thesolution line, and to fluidly connect the spike and the connector end ofthe solution line after the caps are removed.

In another aspect of the invention, a dialysis machine may include a capstripper that is arranged to remove one or more caps on a connector endof a solution line, remove one or more spike caps from spikes on a fluidhandling cassette, and to retain and reattach the caps to the solutionlines and the spike caps to the spikes on the cassette.

In another aspect of the invention, a fluid line connection system for aperitoneal dialysis system includes a fluid handling cassette having agenerally planar body with at least one pump chamber formed as adepression in a first side of the body and a plurality of flowpaths forfluid, a plurality of dialysate solution line spikes located at a firstend of the body, the solution line spikes being in fluid communicationwith the at least one pump chamber via at least one flowpath andarranged so that the spikes are generally co-planar with the generallyplanar body of the fluid handing cassette, and a carriage arranged toreceive a plurality of solution lines, where each solution line has aconnector end. The carriage may be arranged to automatically fluidlyconnect a connector end of a solution line with a corresponding spike.

In one embodiment, the carriage is arranged to move the solution linesand respective caps along a first direction substantially parallel tothe generally planar body of the fluid handling cassette. A carriagedrive that moves the carriage only the first direction may include adrive element and a pneumatic bladder or screw drive to move the driveelement along the first direction. A cap stripper may be provided thatis arranged to remove one or more caps from a connector end of asolution line, and remove one or more spike caps from a spike on thecassette while the one or more caps are secured to a corresponding oneof the spike caps. In one embodiment, the cap stripper may be arrangedto r retain and reattach the caps to the solution lines and the spikecaps to the spikes on the cassette.

In another aspect of the invention, a peritoneal dialysis system mayinclude a cycler device with components suitable for controllingdelivery of dialysate to the peritoneal cavity of a patient. The cyclerdevice may have a housing that encloses at least some of the componentsand have a heater bag receiving section. (The term “heater bag” is usedherein to refer to any suitable container to heat dialysate, such as aflexible or rigid container, whether made of polymer, metal or othersuitable material.) A lid may be mounted to the housing and be movablebetween an open position in which a heater bag is placeable in theheater bag receiving section and a closed position in which the lidcovers the heater bag receiving section. Such an arrangement may allowfor faster or more efficient heating of dialysate in the heater bag,e.g., because heat may be retained by the lid. Also, the lid may helpprevent human touch of potentially hot surfaces.

In one embodiment, the dialysis system may include a fluid handlingcassette with a heater bag port attached to a heater bag line, a patientport attached to a patient line, and at least one pump chamber to movefluid in the patient line and the heater bag line. A heater bag may beattached to the heater bag line and be arranged for placement in theheater bag receiving section.

In another embodiment, the system may include an interface (such as avisual display with a touch screen component) that is movably mounted tothe housing and is movable between a first position in which theinterface is received in the heater bag receiving section, and a secondposition in which the interface is located out of the heater bagreceiving section (e.g., a position in which a user may interact withthe interface). Thus, the interface may be hidden from view when thesystem is idle, allowing the interface to be protected. Also, storingthe interface in the heater bag receiving section may make the systemmore compact, at least in an “as stored” condition.

In another aspect of the invention, a dialysis system includes a supplyof pneumatic pressure and/or vacuum suitable for controllingpneumatically-operated components of the system, apneumatically-operated component that is fluidly connected to the supplyof pneumatic pressure and/or vacuum, and a control system that providespneumatic pressure or vacuum to the pneumatically-operated component andsubsequently isolates the pneumatically-operated component from thesupply of pneumatic pressure or vacuum for a substantial period of timebefore again providing pneumatic pressure or vacuum to thepneumatically-operated component. Such an arrangement may be useful forcomponents that are actuated relatively infrequently, such as theoccluder arrangement described herein. Small motions of some componentsmay cause the component to emit noise that may be found bothersome by apatient. By isolating the component from the pneumatic pressure/vacuum,the component may avoid slight movement caused by variations in thesupply pressure/vacuum, e.g., resulting from draws on thepressure/vacuum by other system components. In one embodiment, thesubstantial period of time may be 5 minutes or more, 1 hour or more, 50%or more of a time period required to deliver or remove a volume ofdialysate suitable for a dialysis treatment with respect to a patient'speritoneal cavity, or other suitable periods.

In another aspect of the invention, a dialysis system includes a supplyof pneumatic pressure and/or vacuum suitable for controllingpneumatically-operated components of the system, apneumatically-operated component that is fluidly connected to the supplyof pneumatic pressure and/or vacuum, and a control system that providespneumatic pressure or vacuum to the pneumatically-operated component andcontrols the pneumatic pressure or vacuum so as to reduce noisegenerated by the pneumatically-operated component. For example, thepneumatically-operated component may include at least one moving part(such as a pump diaphragm), and the control system may reduce thepneumatic pressure or vacuum provided to the pneumatically-operatedcomponent so as to slow movement of the moving part as the moving partstops and/or changes direction (e.g., the pressure/vacuum may becontrolled to slow movement of the diaphragm before the diaphragmchanges direction). In another embodiment, a pulse width modulationcontrol of a pressure/vacuum supply valve may be used, e.g., to reducenoise emitted by moving parts of the valve.

In another aspect of the invention, a dialysis system includes a supplyof pneumatic pressure and vacuum suitable for controllingpneumatically-operated components of the system. A firstpneumatically-operated component may be fluidly connected to the supplyof pneumatic pressure and/or vacuum, and have a first output line torelease pneumatic pressure. A second pneumatically-operated componentmay be fluidly connected to the supply of pneumatic pressure and/orvacuum, and have a second output line to release pneumatic vacuum. Aspace, such as that defined by an accumulator, manifold orsound-insulated chamber, may be fluidly connected to both the first andsecond output lines. A control system may provide pneumatic pressure orvacuum to the pneumatically-operated components so that when the firstand second components release pressure/vacuum during operation, thereleased pressure/vacuum may be received into the common space (e.g., amanifold). In some circumstances, gas under positive pressure releasedby components may be balanced by negative pressure released by othercomponents, thus reducing noise generated.

In another aspect of the invention, a peritoneal dialysis system mayinclude a fluid handling cassette having a patient line fluidlyconnected to and leading from the peritoneal cavity of a patient, andwhich includes at least one pump chamber to move dialysate solution inthe patient line. A cycler device may be arranged to receive andinteract with the fluid handling cassette and cause the at least onepump chamber to move dialysate solution in the patient line. The cyclermay include a control system arranged to control the at least one pumpchamber to operate in a priming operation to force dialysate solutioninto the patient line so as to remove any air in the patient line, andmay be adapted to interact with two types of fluid handling cassettesthat differ with respect to a volume of the patient line connected tothe cassette body. A first type of cassette may have a relatively lowvolume patient line (e.g., for pediatric applications), and a secondtype of cassette may have a relatively high volume patient line (e.g.,for adult applications), and the control system may detect whether acassette received by the cycler is a first type or a second type and toadjust cycler operation accordingly.

In one embodiment, the control system may detect whether a cassettereceived by the cycler is a first type or a second type by determiningthe volume of the patient line during priming, and to adjust the amountof fluid moved through the cassette during operation of the system. Inanother embodiment, indicia, such as a barcode, on the cassette may bedetected by the cycler and cause the cycler to adjust a pumpingoperation based on the type of cassette.

In another aspect of the invention, a dialysis machine includes a fluidhandling cassette having a plurality of spikes and at least one pumpchamber to move fluid in the spikes, a plurality of solution lines eachengaged with a respective spike on the cassette, and a control systemthat reads indicia on each of the solution lines to determine a type foreach of the solution lines. The control system may adjust a pumpingoperation or other cycler operation based in the identity of one or moreof the solution lines. For example, a solution line may be identified asbeing an effluent sampling line and the pumping operation may beadjusted to direct used dialysate from a patient to the effluentsampling line during a drain cycle.

In another aspect of the invention, a method of automatically recoveringfrom a tilt condition in a dialysis system may include (A) detecting anangle of tilt of at least a portion of a dialysis system, the portion ofthe dialysis system including machinery for performing a dialysistherapy, (B) determining that a tilt condition exists in which the angleof tilt exceeds a predetermined threshold, (C) in response to (B),pausing the dialysis therapy, (D) monitoring the angle of tilt while thedialysis therapy is paused, (E) determining that the tilt condition nolonger exists, and (F) in response to (E), automatically resuming thedialysis therapy.

In another aspect of the invention, a patient data interface for adialysis system includes a device port comprising a recess in a chassisof at least a portion of the dialysis system and a first connectordisposed within the recess. A patient data storage device may include ahousing and a second connector coupled to the housing, where the secondconnector is adapted to be selectively coupled to the first connector.The recess may have a first shape and the housing may have a secondshape corresponding to the first shape such that when the first andsecond connectors are coupled, the housing of the patient data storagedevice is received at least partially within the recess. The first andsecond shapes may be irregular and the patient data storage device mayhave a verification code that is readable by the dialysis system toverify that the patient data storage device is of an expected typeand/or origin.

In another aspect of the invention, a method for providing peritonealdialysis includes delivering or withdrawing dialysate with respect tothe patient's peritoneal cavity at a first pressure, and adjusting apressure at which dialysate is delivered or withdrawn to minimizepatient sensation of dialysate movement. In one embodiment, the pressuremay be adjusted during a same fill or empty cycle of a peritonealdialysis therapy, and/or within different fill or empty cycles of aperitoneal dialysis therapy. For example, when withdrawing dialysatefrom a patient, the pressure at which dialysate is withdrawn may bereduced when an amount of dialysate remaining in the peritoneal cavitydrops below a threshold volume. Reducing the pressure (negative pressureor vacuum) near the end of a drain cycle may reduce the sensation thepatient may have of the dialysate withdrawal.

In another aspect of the invention, a method for providing peritonealdialysis includes providing a first solution to a patient's peritonealcavity using a reusable cycler device during a first treatment ofperitoneal dialysis, and providing a second solution to the patient'speritoneal cavity using the reusable cycler device during a secondtreatment of peritoneal dialysis immediately subsequent to the firsttreatment, where the second solution has a different chemical makeuprelative to the first solution. The different solutions may be createdby mixing liquid material from two or more solution containers that areconnected to the cycler (e.g., via a cassette mounted to the cycler).The solution containers may be automatically identified by the cycler,e.g., by reading a barcode, RFID tag, or other indicia.

In another aspect of the invention, a medical infusion system includes ahousing that encloses at least some of the components of the system, anda control surface attached to the housing and constructed and arrangedto control the operation of a fluid handling cassette that may beremovably mounted to the housing. The control surface may have aplurality of movable portions arranged to control fluid pumping andvalve operations of the cassette, and at least one of the movableportions may have an associated vacuum port arranged to draw fluid froma region near the movable portion.

In one embodiment, the control surface includes a sheet of resilientpolymer material, and each of the movable portions may have anassociated vacuum port. In another embodiment, the cassette includes amembrane that is positionable adjacent the control surface, and thevacuum port is arranged to remove fluid from a space between themembrane and the control surface. A liquid sensor may be arranged todetect liquid drawn into the vacuum port, e.g., in case the membraneruptures, allowing liquid to leak from the cassette.

In another aspect of the invention, a volume of fluid moved by a pump,such as a pump in an APD system, may be determined based on pressuremeasurement and certain known chamber and/or line volumes, but withoutdirect measurement of the fluid, such as by flow meter, weight, etc. Inone embodiment, a volume of a pump chamber having a movable element thatvaries the volume of the pump chamber may be determined by measuringpressure in the pump chamber, and a reference chamber both whileisolated from each other, and after the two chambers are fluidlyconnected so that pressures in the chambers may equalize. In oneembodiment, equalization of the pressures may be assumed to occur in anadiabatic way, e.g., a mathematical model of the system that is based onan adiabatic pressure equalization process may be used to determine thepump chamber volume. In another embodiment, pressures measured after thechambers are fluidly connected may be measured at a time before completeequalization has occurred, and thus the pressures for the pump andreference chambers measured after the chambers are fluidly connected maybe unequal, yet still be used to determine the pump chamber volume. Thisapproach may reduce a time between measurement of initial and finalpressures, thus reducing a time during which heat transfer may takeplace and reducing error that may be introduced given the adiabaticmodel used to determine the pump chamber volume.

In one aspect of the invention, a method for determining a volume offluid moved by a pump includes measuring a first pressure for a pumpcontrol chamber when the pump control chamber is isolated from areference chamber. The pump control chamber may have a volume thatvaries at least in part based on movement of a portion of the pump, suchas a pump membrane or diaphragm. A second pressure may be measured forthe reference chamber when the reference chamber is isolated from thepump control chamber. The reference chamber may have a known volume. Athird pressure associated with the pump control chamber after fluidlyconnecting the reference chamber and the pump control chamber may bemeasured, but the measurement may occur before substantial equalizationof pressures between the pump control and reference chambers hasoccurred. Similarly, a fourth pressure associated with the referencechamber after fluidly connecting the reference chamber and the pumpcontrol chamber may be measured, but before substantial equalization ofpressures between the pump control and reference chambers has occurred.A volume for the pump control chamber may be determined based on thefirst, second, third and fourth measured pressures.

In one embodiment, the third and fourth pressures are measured atapproximately a same time and the third and fourth pressures aresubstantially unequal to each other. For example, equalization of thepressures in the pump control and reference chambers may occur after anequalization time period once the pump control and reference chambersare fluidly connected, but the third and fourth pressures may bemeasured at a time after the pump control and reference chambers arefluidly connected that is approximately 10% to 50% of the equalizationtime period. Thus, the third and fourth pressures may be measured longbefore (in time sense) the pressures in the chambers have fullyequalized. In another embodiment, the third and fourth pressures may bemeasured at a time when the pressures in the chambers has reachedapproximately 50-70% equalization, e.g., the pressures in the chambershave changed from an initial value that is within about 50-70% of anequalized pressure value. Thus, a time period between measurement of thefirst and second pressures and measurement of the third and fourthpressures may be minimized.

In another embodiment, a model for determining the volume of the pumpcontrol chamber may incorporate an assumption that an adiabatic systemexists from a point in time when the first and second pressures aremeasured for the isolated pump control chamber and the reference chamberuntil a point in time when the third and fourth pressures are measured.

To determine a volume of fluid moved by the pump, the steps of measuringthe first, second, third and fourth pressures and the step ofdetermining may be performed for two different positions of a pumpmembrane to determine two different volumes for the pump controlchamber. A difference between the two different volumes may represent avolume of fluid delivered by the pump.

As mentioned above, this aspect of the invention may be used in anysuitable system, such as a system in which the pump is part of adisposable cassette and the pump control chamber is part of a dialysismachine used in a dialysis procedure.

In one embodiment, the first and/or second pressure may be selected froma plurality of pressure measurements as coinciding with a point in timeat which a pressure in the pump control chamber or reference chamber (asappropriate) first begins to change from a previously stable value. Forexample, the point in time may be identified based on a determination ofwhen a best fit line for a plurality of consecutive sets of measuredpressures first deviates from a constant slope. This approach may helpidentify initial pressures for the pump control and reference chambersthat are as late in time as possible, while reducing error in the pumpvolume determination.

In another embodiment, a technique may be used to identify an optimalpoint in time at which the third and fourth pressures are measured. Forexample, a plurality of pressure values for the pump control chamber maybe measured after the pump control and reference chambers are fluidlyconnected, and a plurality of change in volume values may be determinedfor the pump control chamber based on the plurality of pressure valuesfor the pump control chamber. Each of the plurality of change in volumevalues may corresponding to a unique point in time and a measuredpressure value for the pump chamber. In this case, the change in volumevalues are due to movement of an imaginary piston that is present at thevalve or other component that initially isolates the pump control andreference chambers, but moves upon opening of the valve or othercomponent. Thus, the pump chamber does not actually change size orvolume, but rather the change in volume is an imaginary condition due tothe pressures in the pump chamber and reference chamber being differentfrom each other initially. Similarly, a plurality of pressure values forthe reference chamber may be measured after the pump control andreference chambers are fluidly connected, and a plurality of change involume values for the reference chamber may be determined based on theplurality of pressure values for the reference chamber. Each of theplurality of change in volume values may correspond to a unique point intime and a measured pressure value for the reference chamber, and likethe change in volume values for the pump chamber, are a result ofmovement of an imaginary piston. A plurality of difference valuesbetween change in volume values for the pump control chamber and for thereference chamber may be determined, with each difference value beingdetermined for corresponding change in volume values for the pumpcontrol chamber and change in volume values for the reference chamber,i.e., the pairs of change in volume values for which a difference valueis determined correspond to a same or substantially same point in time.The difference values may be analyzed, and a minimum difference value(or a difference value that is below a desired threshold) may indicate apoint in time for which the third and fourth pressures should bemeasured. Thus, the third and fourth pressure values may be identifiedas being equal to the pump control chamber pressure value and thereference chamber pressure value, respectively, that correspond to adifference value that is a minimum or below a threshold.

In another embodiment, the pressures measured are pressures of a gaswithin the pump control chamber and the reference chamber, theequalization of pressures within the pump control chamber and referencechamber is assumed to occur adiabatically, the equalization of pressuresbetween the pump control chamber and reference chamber is assumed toinclude a change in the volume of a gas in the pump control chamber andreference chamber in equal but opposite directions, and the volume ofgas in the reference chamber at the time of the fourth pressuremeasurement is calculated from the known volume of the referencechamber, and the second and fourth pressures. The change in volume ofgas in the reference chamber may be assumed to be the difference betweenthe known volume of the reference chamber and the calculated value ofthe volume of gas in the reference chamber at the time of the fourthpressure measurement. Also, the change in volume of gas in the pumpcontrol chamber may be assumed to be the difference between the initialvolume of the pump control chamber and the volume of gas in the pumpcontrol chamber at the time of the third pressure measurement, whereinthe change in volume of gas in the pump control chamber is equal to butopposite the change in volume of gas in the reference chamber.

In another aspect of the invention, a method for determining a volume offluid moved by a pump includes providing a fluid pump apparatus having apump chamber separated from a pump control chamber by a movablemembrane, and a reference chamber that is fluidly connectable to thepump control chamber, adjusting a first pressure in the pump controlchamber to cause the membrane to move and thereby move fluid in the pumpchamber, isolating the reference chamber from the pump control chamberand establishing a second pressure in the reference chamber that isdifferent from a pressure in the pump control chamber, fluidlyconnecting the reference chamber and the pump control chamber toinitiate equalization of pressures in the pump control chamber and thereference chamber, and determining a volume for the pump control chamberbased on the first and second pressures, and an assumption that thepressures in the pump control and reference chambers initiateequalization in an adiabatic way.

In one embodiment, third and fourth pressures for the pump control andreference chambers, respectively, may be measured after fluidlyconnecting the reference chamber and the pump control chamber, and thethird and fourth pressures may be used to determine the volume for thepump control chamber. The third and fourth pressures may besubstantially unequal to each other. Similar to that mentioned above,the adjusting, isolating, fluidly connecting and determining steps maybe repeated, and a difference between the two determined volumes for thepump control chamber may be determined, where the difference representsa volume of fluid delivered by the pump.

In another embodiment, the pump is part of a disposable cassette and thepump control chamber is part of a dialysis machine used in a dialysisprocedure.

In another aspect of the invention, a medical infusion system includes apump control chamber, a control surface associated with the pump controlchamber so that at least a portion of the control surface is movable inresponse to a pressure change in the pump control chamber, a fluidhandling cassette having at least one pump chamber positioned adjacentthe control surface and arranged so that fluid in the at least one pumpchamber moves in response to movement of the portion of the controlsurface, a reference chamber that is fluidly connectable to the pumpcontrol chamber, and a control system arranged to adjust a pressure inthe pump control chamber and thus control movement of fluid in the pumpchamber of the fluid handling cassette. The control system may bearranged to measure a first pressure for the pump control chamber whenthe pump control chamber is isolated from the reference chamber, measurea second pressure for the reference chamber when the reference chamberis isolated from the pump control chamber, fluidly connect the pumpcontrol chamber and the reference chamber, measure third and fourthpressures associated with the pump control chamber and the referencechamber, respectively, after fluidly connecting the reference chamberand the pump control chamber, and determine a volume for the pumpcontrol chamber based on the first, second, third and fourth measuredpressures and a mathematical model that defines equalization of pressurein the pump control and reference chambers as occurring adiabaticallywhen the pump control and reference chambers are fluidly connected.

In one embodiment, the third and fourth pressures are substantiallyunequal to each other, e.g., the third and fourth pressures may bemeasured prior to substantial equalization of pressures in the pumpcontrol and reference chambers.

In another aspect of the invention, a method for determining a volume offluid moved by a pump includes measuring a first pressure for a pumpcontrol chamber when the pump control chamber is isolated from areference chamber, the pump control chamber having a volume that variesat least in part based on movement of a portion of the pump, measuring asecond pressure for the reference chamber when the reference chamber isisolated from the pump control chamber, measuring a third pressureassociated with both the pump control chamber and the reference chamberafter fluidly connecting the reference chamber and the pump controlchamber, and determining a volume for the pump control chamber based onthe first, second and third measured pressures.

In one embodiment, the third pressure may be measured after completeequalization of pressures in the pump control and reference chambers iscomplete. In one embodiment, a model used to determine the pump chambervolume may assume an adiabatic system in equalization of pressurebetween the pump chamber and the reference chamber.

In one aspect of the invention, a method for determining a presence ofair in a pump chamber includes measuring a pressure for a pump controlchamber when the pump control chamber is isolated from a referencechamber, the pump control chamber having a known volume and beingseparated from a pump chamber, that is at least partially filled withliquid, by a membrane, measuring a pressure for the reference chamberwhen the reference chamber is isolated from the pump control chamber,the reference chamber having a known volume, measuring a pressure afterfluidly connecting the reference chamber and the pump control chamberand prior to a time when the pressure in the chambers has equalized, anddetermining a presence or absence of an air bubble in the pump chamberbased on the measured pressures and known volumes.

In one embodiment, a model used to determine the presence or absence ofan air bubble assumes an adiabatic system from a point in time when thepressures are measured for the isolated pump control chamber and thereference chamber until a point in time after the chambers are fluidlyconnected. In another embodiment, the pressure for the pump controlchamber is measured with the membrane drawn toward a wall of the pumpcontrol chamber.

In another aspect of the invention, an automated peritoneal dialysissystem includes a reusable cycler that is constructed and arranged forcoupling to a disposable fluid handling cassette containing at least onepumping chamber. The disposable fluid handling cassette may beconfigured to be connected in fluid communication with the peritoneum ofa patient via a first collapsible tube and with a second source and/ordestination (such as a solution container line) via a second collapsibletube. An occluder may be configured and positioned within the cycler toselectively occlude the first collapsible tube while not occluding thesecond collapsible tube. In one embodiment, the occluder can occlude aplurality of collapsible tubes, such as a patient line, a drain lineand/or a heater bag line. The cassette may have a generally planar bodywith at least one pump chamber formed as a depression in a first side ofthe body and a plurality of flowpaths for fluid, a patient line portlocated at a first end of the body arranged for connection to the firstcollapsible tube, and a solution line port located at a second end ofthe body opposite the first end, and arranged for connection to thesecond collapsible tube. The occluder may be configured and positionedwithin the cycler to selectively occlude the first tube and a thirdcollapsible tube (e.g., for a drain) while not occluding the secondcollapsible tube.

In another embodiment, the occluder includes first and second opposedoccluding members pivotally connected to each other, a tube contactingmember connected to, or comprising at least a portion of, at least oneof the first and second occluding members, and a force actuatorconstructed and positioned to apply a force to at least one of the firstand second occluding members. Application of the force by the forceactuator may cause the tube contacting members to move between a tubeoccluding and an open position. The occluder may include a releasemember configured and positioned to enable an operator to manually movethe tube contacting member from the tube occluding position to the openposition even with no force applied to the occluding member by the forceactuator. The force actuator may apply a force sufficient to bend boththe first and second occluding members, so that upon application of theforce by the force actuator to bend the first and second occludingmembers, the tube contacting member may move between a tube occludingand an open position. The occluding members may be spring platespivotally connected together at opposite first and second ends, and thetube contacting member may be a pinch head connected to the springplates at the first ends, while the second ends of the spring plates maybe affixed directly or indirectly to a housing to which the occluder isconnected. In one embodiment, the force actuator comprises an inflatablebladder positioned between the first and second occluding members. Theforce actuator may increase a distance between the first and secondoccluding members in a region where the first and second occludingmembers are in opposition so as to move the tube contacting memberbetween a tube occluding and an open position. In one embodiment, theforce actuator may bend one or both of the occluding members to move thetube contacting member from a tube occluding position to an openposition.

Various aspects of the invention are described above and below withreference to illustrative embodiments. It should be understood that thevarious aspects of the invention may be used alone and/or in anysuitable combination with other aspects of the invention. For example,the pump volume determination features described herein may be used witha liquid handling cassette having the specific features described, orwith any other suitable pump configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the invention are described below with reference toillustrative embodiments that are shown, at least in part, in thefollowing figures, in which like numerals reference like elements, andwherein:

FIG. 1 shows a schematic view of an automated peritoneal dialysis (APD)system that incorporates one or more aspects of the invention;

FIG. 1A shows an alternative arrangement for a dialysate delivery setshown in FIG. 1;

FIG. 2 is a schematic view of an illustrative set for use with the APDsystem of FIG. 1;

FIG. 3 is an exploded perspective view of a cassette in a firstembodiment;

FIG. 4 is a cross sectional view of the cassette along the line 4-4 inFIG. 3;

FIG. 5 is a perspective view of a vacuum mold that may be used to form amembrane having pre-formed pump chamber portions in an illustrativeembodiment;

FIG. 6 shows a front view of the cassette body of FIG. 3;

FIG. 7 is a front view of a cassette body including two different spacerarrangements in an illustrative embodiment;

FIG. 8 is a rear perspective view of the cassette body of FIG. 3;

FIG. 9 is a rear view of the cassette body of FIG. 3;

FIG. 9-1A is a front perspective view of an exemplary configuration of apatient line state detector or liquid level detector;

FIG. 9-1B is a rear perspective view of a patient line state detector orliquid level detector;

FIG. 9-2 is a perspective layout view of three LEDs and an opticaldetector surface-mounted on a printed circuit board;

FIG. 9-3 is a plan view of three LEDs and an optical detector mounted ona detector circuit board;

FIG. 9-4 is an exploded perspective view of the detector of FIG. 9-1showing the printed circuit board and transparent or translucent plasticinsert.

FIG. 9-5 is a perspective view of an alternative configuration of aliquid level detector;

FIG. 9-6 is a perspective view of the front of an unloaded organizer(absent any solution lines);

FIG. 9-7 is a back view of the organizer of FIG. 9-6;

FIG. 9-8 is a perspective view of an organizer including a plurality ofsolution lines, a patient line, and a drain line;

FIG. 9-9 is a perspective view of an organizer clip;

FIG. 9-10 is a perspective view of an organizer clip receiver;

FIG. 9-11 is a perspective view of a door latch sensor assemblyassociated with a cycler;

FIG. 9-11 a is a cross-sectional view of the door latch sensor assemblyof FIG. 9-11;

FIG. 9-12 is a graph showing the ability of the liquid level detector ofFIG. 9-1 to distinguish between a primed and a non-primed patient line;

FIG. 9-12 a is a graph showing the range of signals corresponding to aprimed and a non-primed patient line for different cyclers using theliquid detector of FIG. 9.1;

FIG. 9-13 is a graph showing measurements collected by an optical sensorcomparing liquid detection using an orthogonally oriented LED vs. anangled LED;

FIG. 9-14 is a graph showing the ability of the liquid level detector ofFIG. 9-1 to distinguish between the presence and absence of a tubingsegment within the detector;

FIG. 10 is a perspective view of the APD system of FIG. 1 with the doorof the cycler in an open position;

FIG. 11 is a perspective view of the inner side of the door of thecycler show in FIG. 10;

FIG. 11-1 is a perspective view of a carriage in a first embodiment;

FIG. 11-2 is an enlarged perspective view of a solution line loaded intothe carriage of FIG. 11-1;

FIG. 11-3 is a perspective view of an open identification tag;

FIG. 11-4 is a perspective view of a carriage drive assembly includingan AutoID camera mounted to an AutoID camera board;

FIG. 11-5 is a perspective view of an embodiment for a stripper elementof a cap stripper;

FIG. 11-6 is a front perspective view of the carriage drive assembly ofFIG. 11-4 showing the position of the stripper element of FIG. 11-5within the carriage drive assembly;

FIG. 11-7 a shows a perspective view of a portion of the stripperelement of FIG. 11-5, in which a spike cap is positioned;

FIG. 11-7 b shows a perspective view of a portion of the stripperelement of FIG. 11-5, in which a solution line cap is positioned over aspike cap;

FIG. 11-7 c shows a perspective view of a portion of the stripperelement of FIG. 11-5, showing a sensor element and rocker arm in theabsence of a spike cap;

FIG. 12 is a right front perspective view of a carriage drive assemblyand cap stripper in a first embodiment;

FIG. 13 a left front perspective view of the carriage drive assembly andcap stripper of FIG. 12;

FIG. 14 is a partial rear view of the carriage drive assembly of FIG.12;

FIG. 15 is a rear perspective view of a carriage drive assembly in asecond illustrative embodiment;

FIG. 16 is a left rear perspective view of the carriage drive assemblyand cap stripper of FIG. 15;

FIG. 17 is a left front perspective view of a cap stripper element in anillustrative embodiment;

FIG. 18 is a right front perspective view of the cap stripper element ofFIG. 17;

FIG. 19 is a front view of the cap stripper element of FIG. 17;

FIG. 20 is a cross sectional view along the line 20-20 in FIG. 19;

FIG. 21 is a cross sectional view along the line 21-21 in FIG. 19;

FIG. 22 is a cross sectional view along the line 22-22 in FIG. 19;

FIG. 23 is a close-up exploded view of the connector end of a solutionline in an illustrative embodiment;

FIG. 24 is a schematic view of a cassette and solution lines beingloaded into the cycler of FIG. 10;

FIG. 25 is a schematic view of the cassette and solution lines afterplacement in respective locations of the door of the cycler of FIG. 10;

FIG. 26 is a schematic view of the cassette and solution lines after thedoor of the cycler is closed;

FIG. 27 is a schematic view of the solution lines being engaged withspike caps;

FIG. 28 is a schematic view of the cap stripper engaging with spike capsand solution line caps;

FIG. 29 is a schematic view of the solution lines with attached caps andspike caps after movement away from the cassette;

FIG. 30 is a schematic view of the solution lines after movement awayfrom the solution line caps and spike caps;

FIG. 31 is a schematic view of the cap stripper retracting with thesolution line caps and spike caps;

FIG. 32 is a schematic view of the solution lines being engaged with thespikes of the cassette;

FIG. 33 is a cross sectional view of a cassette with five stages of asolution line connection operation shown with respect to correspondingspikes of the cassette;

FIG. 34 shows a rear view of a cassette in another illustrativeembodiment including different arrangements for a rear side of thecassette adjacent the pump chambers;

FIG. 35 shows an end view of a spike of a cassette in an illustrativeembodiment;

FIG. 35A shows a perspective view of an alternative embodiment of thespikes of a cassette;

FIG. 35B shows an embodiment of a spike cap configured to fit over thespikes shown in FIG. 35A;

FIG. 35C shows a cross-sectional view of a spike cap shown in FIG. 35B;

FIG. 36 shows a front view of a control surface of the cycler forinteraction with a cassette in the FIG. 10 embodiment;

FIG. 36A shows a front view and selected cross-sectional views of anembodiment of a control surface of the cycler;

FIG. 37 shows an exploded view of an assembly for the interface surfaceof FIG. 36, with the mating pressure delivery block and pressuredistribution module;

FIG. 37A shows an exploded view of the integrated manifold;

FIG. 37B shows two isometric views of the integrated manifold;

FIG. 37C shows an schematic of the pneumatic system that controls fluidflow through the cycler;

FIG. 38 shows an exploded perspective view of an occluder in anillustrative embodiment;

FIG. 39 shows a partially exploded perspective view of the occluder ofFIG. 38;

FIG. 40 shows a top view of the occluder of FIG. 38 with the bladder ina deflated state;

FIG. 41 shows a top view of the occluder of FIG. 38 with the bladder inan inflated state;

FIG. 42 is a schematic view of a pump chamber of a cassette andassociated control components and inflow/outflow paths in anillustrative embodiment;

FIG. 43 is a plot of illustrative pressure values for the controlchamber and the reference chamber from a point in time before opening ofthe valve X2 until some time after the valve X2 is opened for theembodiment of FIG. 42;

FIG. 44 is a perspective view of an interior section of the cycler ofFIG. 10 with the upper portion of the housing removed;

FIG. 45 is a schematic block diagram illustrating an exemplaryimplementation of control system for an APD system;

FIG. 45A is a schematic block diagram illustrating an exemplaryarrangement of the multiple processors controlling the cycler and thesafe line;

FIG. 45B is a schematic block diagram illustrating exemplary connectionsbetween the hardware interface processor and the sensors, the actuatorsand the automation computer;

FIG. 46 is a schematic block diagram of illustrative software subsystemsof a user interface computer and the automation computer for the controlsystem of FIG. 45;

FIG. 47 shows a flow of information between various subsystems andprocesses of the APD system in an illustrative embodiment;

FIG. 48 illustrates an operation of the therapy subsystem of FIG. 46;

FIG. 49 shows a sequence diagram depicting exemplary interactions oftherapy module processes during initial replenish and dialyze portionsof the therapy;

FIG. 49-1 shows a schematic cross section of the cycler illustrating thecomponents of the heater system for the heater bag;

FIG. 49-2 shows the software processes interacting with the heatercontroller process;

FIG. 49-3 shows the block diagram of a nested feedback loop to controlthe heater bag temperature;

FIG. 49-4 shows the block diagram of an alternative nested feedback loopto control the heater bag temperature;

FIG. 49-5 shows the block diagram of another alternative nested feedbackloop to control the heater bag temperature;

FIG. 49-6 shows the block diagram of the thermal model of the heater bagand heater tray;

FIG. 49-7 shows the temperature response of the heater bag and heatertray for nominal conditions;

FIG. 49-8 shows the temperature response of the heater bag and heatertray for warm conditions;

FIG. 49-9 shows the temperature response of the heater bag and heatertray for cold conditions;

FIG. 49-10 is a schematic block diagram of one embodiment of a heatercontrol system;

FIG. 49-11 is a is a schematic block diagram illustrating a heatercircuit configured with a pair of heating elements;

FIG. 49-12 is a is a schematic block diagram illustrating a heatercircuit configured with a pair of heating elements with reducedpotential for current leakage;

FIG. 49-13 is a circuit diagram of a heater circuit configured with apair of heating elements;

FIG. 49-14 shows a flow chart diagram illustrating a method to selectthe heater configuration in an APD cycler, according to one embodimentof the present invention; and

FIG. 49-15 shows a flow chart diagram illustrating a method to selectthe heater configuration in an APD cycler where a stored value of the ACmains voltage is queried during selection of the heater configuration,according to one embodiment of the present invention.

FIGS. 50-55 show exemplary screen views relating to alerts and alarmsthat may be displayed on a touch screen user interface for the APDsystem;

FIG. 56 illustrates component states and operations for error conditiondetection and recovery in an illustrative embodiment;

FIG. 57 shows exemplary modules of a UI view subsystem for the APDsystem;

FIGS. 58-64 shows illustrative user interface screens for providing userinformation and receiving user input in illustrative embodimentsregarding system setup, therapy status, display settings, remoteassistance, and parameter settings;

FIG. 65 shows an exemplary patient data key and associated port fortransferring patient data to and from the APD system;

FIG. 65A shows a patient data key with an alternative housingconfiguration.

FIG. 66 shows an exemplary pressure tracing from a control or actuationchamber of a pumping cassette during a liquid delivery stroke;

FIG. 67 shows an illustration of an adaptive tidal therapy mode duringCCPD;

FIG. 68 shows an illustration of the implementation of a revised-cyclemode during CCPD;

FIG. 69 shows an illustration of the implementation of a revised-cyclemode during a tidal therapy; and

FIG. 70 shows an illustration of the implementation of an adaptive tidalmode during a tidal therapy.

DETAILED DESCRIPTION

Although aspects of the invention are described in relation to aperitoneal dialysis system, certain aspects of the invention can be usedin other medical applications, including infusion systems such asintravenous infusion systems or extracorporeal blood flow systems, andirrigation and/or fluid exchange systems for the stomach, intestinaltract, urinary bladder, pleural space or other body or organ cavity.Thus, aspects of the invention are not limited to use in peritonealdialysis in particular, or dialysis in general.

APD System

FIG. 1 shows an automated peritoneal dialysis (APD) system 10 that mayincorporate one or more aspects of the invention. As shown in FIG. 1,for example, the system 10 in this illustrative embodiment includes adialysate delivery set 12 (which, in certain embodiments, can be adisposable set), a cycler 14 that interacts with the delivery set 12 topump liquid provided by a solution container 20 (e.g., a bag), and acontrol system 16 (e.g., including a programmed computer or other dataprocessor, computer memory, an interface to provide information to andreceive input from a user or other device, one or more sensors,actuators, relays, pneumatic pumps, tanks, a power supply, and/or othersuitable components—only a few buttons for receiving user control inputare shown in FIG. 1, but further details regarding the control systemcomponents are provided below) that governs the process to perform anAPD procedure. In this illustrative embodiment, the cycler 14 and thecontrol system 16 are associated with a common housing 82, but may beassociated with two or more housings and/or may be separate from eachother. The cycler 14 may have a compact footprint, suited for operationupon a table top or other relatively small surface normally found in thehome. The cycler 14 may be lightweight and portable, e.g., carried byhand via handles at opposite sides of the housing 82.

The set 12 in this embodiment is intended to be a single use, disposableitem, but instead may have one or more reusable components, or may bereusable in its entirety. The user associates the set 12 with the cycler14 before beginning each APD therapy session, e.g., by mounting acassette 24 within a front door 141 of the cycler 14, which interactswith the cassette 24 to pump and control fluid flow in the various linesof the set 12. For example, dialysate may be pumped both to and from thepatient to effect APD. Post therapy, the user may remove all or part ofthe components of the set 12 from the cycler 14.

As is known in the art, prior to use, the user may connect a patientline 34 of the set 12 to his/her indwelling peritoneal catheter (notshown) at a connection 36. In one embodiment, the cycler 14 may beconfigured to operate with one or more different types of cassettes 24,such as those having differently sized patient lines 34. For example,the cycler 14 may be arranged to operate with a first type of cassettewith a patient line 34 sized for use with an adult patient, and a secondtype of cassette with a patient line 34 sized for an infant or pediatricuse. The pediatric patient line 34 may be shorter and have a smallerinner diameter than the adult line so as to minimize the volume of theline, allowing for more controlled delivery of dialysate and helping toavoid returning a relatively large volume of used dialysate to thepediatric patient when the set 12 is used for consecutive drain and fillcycles. A heater bag 22, which is connected to the cassette 24 by a line26, may be placed on a heater container receiving portion (in this case,a tray) 142 of the cycler 14. The cycler 14 may pump fresh dialysate(via the cassette 24) into the heater bag 22 so that the dialysate maybe heated by the heater tray 142, e.g., by electric resistance heatingelements associated with the tray 142 to a temperature of about 37degrees C. Heated dialysate may be provided from the heater bag 22 tothe patient via the cassette 24 and the patient line 34. In analternative embodiment, the dialysate can be heated on its way to thepatient as it enters, or after it exits, the cassette 24 by passing thedialysate through tubing in contact with the heater tray 142, or throughan in-line fluid heater (which may be provided in the cassette 24). Useddialysate may be pumped from the patient via the patient line 34 to thecassette 24 and into a drain line 28, which may include one or moreclamps to control flow through one or more branches of the drain line28. In this illustrative embodiment, the drain line 28 may include aconnector 39 for connecting the drain line 28 to a dedicated drainreceptacle, and an effluent sample port 282 for taking a sample of useddialysate for testing or other analysis. The user may also mount thelines 30 of one or more containers 20 within the door 141. The lines 30may also be connected to a continuous or real-time dialysate preparationsystem. (The lines 26, 28, 30, 34 may include a flexible tubing and/orsuitable connectors and other components (such as pinch valves, etc.) asdesired.) The containers 20 may contain sterile peritoneal dialysissolution for infusion, or other materials (e.g., materials used by thecycler 14 to formulate dialysate by mixing with water, or admixingdifferent types of dialysate solutions). The lines 30 may be connectedto spikes 160 of the cassette 24, which are shown in FIG. 1 covered byremovable caps. In one aspect of the invention described in more detailbelow, the cycler 14 may automatically remove caps from one or morespikes 160 of the cassette 24 and connect lines 30 of solutioncontainers 20 to respective spikes 160. This feature may help reduce thepossibility of infection or contamination by reducing the chance ofcontact of non-sterile items with the spikes 160.

In another aspect, a dialysate delivery set 12 a may not have cassettespikes 160. Instead, one or more solution lines 30 may be permanentlyaffixed to the inlet ports of cassette 24, as shown in FIG. 1A. In thiscase, each solution line 30 may have a (capped) spike connector 35 formanual connection to a solution container or dialysate bag 20.

With various connections made, the control system 16 may pace the cycler14 through a series of fill, dwell, and/or drain cycles typical of anAPD procedure. For example, during a fill phase, the cycler 14 may pumpdialysate (by way of the cassette 24) from one or more containers 20 (orother source of dialysate supply) into the heater bag 22 for heating.Thereafter, the cycler 14 may infuse heated dialysate from the heaterbag 22 through the cassette 24 and into the patient's peritoneal cavityvia the patient line 34. Following a dwell phase, the cycler 14 mayinstitute a drain phase, during which the cycler 14 pumps used dialysatefrom the patient via the line 34 (again by way of the cassette 24), anddischarges spent dialysis solution into a nearby drain (not shown) viathe drain line 28.

The cycler 14 does not necessarily require the solution containers 20and/or the heater bag 22 to be positioned at a prescribed head heightabove the cycler 14, e.g., because the cycler 14 is not necessarily agravity flow system. Instead, the cycler 14 may emulate gravity flow, orotherwise suitably control flow of dialysate solution, even with thesource solution containers 20 above, below or at a same height as thecycler 14, with the patient above or below the cycler, etc. For example,the cycler 14 can emulate a fixed head height during a given procedure,or the cycler 14 can change the effective head height to either increaseor decrease pressure applied to the dialysate during a procedure. Thecycler 14 may also adjust the rate of flow of dialysate. In one aspectof the invention, the cycler 14 may adjust the pressure and/or flow rateof dialysate when provided to the patient or drawn from the patient soas to reduce the patient's sensation of the fill or drain operation.Such adjustment may occur during a single fill and/or drain cycle, ormay be adjusted across different fill and/or drain cycles. In oneembodiment, the cycler 14 may taper the pressure used to draw useddialysate from the patient near the end of a drain operation. Becausethe cycler 14 may establish an artificial head height, it may have theflexibility to interact with and adapt to the particular physiology orchanges in the relative elevation of the patient.

Cassette

In one aspect of the invention, a cassette 24 may include patient anddrain lines that are separately occludable with respect to solutionsupply lines. That is, safety critical flow to and from patient line maybe controlled, e.g., by pinching the lines to stop flow, without theneed to occlude flow through one or more solution supply lines. Thisfeature may allow for a simplified occluder device since occlusion maybe performed with respect to only two lines as opposed to occludingother lines that have little or no effect on patient safety. Forexample, in a circumstance where a patient or drain connection becomesdisconnected, the patient and drain lines may be occluded. However, thesolution supply and/or heater bag lines may remain open for flow,allowing the cycler 14 to prepare for a next dialysis cycle; e.g.,separate occlusion of patient and drain lines may help ensure patientsafety while permitting the cycler 14 to continue to pump dialysate fromone or more containers 20 to the heater bag 22 or to other solutioncontainers 20.

In another aspect of the invention, the cassette may have patient, drainand heater bag lines at one side or portion of the cassette and one ormore solution supply lines at another side or portion of the cassette,e.g., an opposite side of the cassette. Such an arrangement may allowfor separate occlusion of patient, drain or heater bag lines withrespect to solution lines as discussed above. Physically separating thelines attached to the cassette by type or function allows for moreefficient control of interaction with lines of a certain type orfunction. For example, such an arrangement may allow for a simplifiedoccluder design because less force is required to occlude one, two orthree of these lines than all lines leading to or away from thecassette. Alternately, this arrangement may allow for more effectiveautomated connection of solution supply lines to the cassette, asdiscussed in more detail below. That is, with solution supply lines andtheir respective connections located apart from patient, drain and/orheater bag lines, an automated de-capping and connection device mayremove caps from spikes on the cassette as well as caps on solutionsupply lines, and connect the lines to respective spikes withoutinterference by the patient, drain or heater bag lines.

FIG. 2 shows an illustrative embodiment of a cassette 24 thatincorporates aspects of the invention described above. In thisembodiment, the cassette 24 has a generally planar body and the heaterbag line 26, the drain line 28 and the patient line 34 are connected atrespective ports on the left end of the cassette body, while the rightend of the cassette body may include five spikes 160 to which solutionsupply lines 30 may be connected. In the arrangement shown in FIG. 2,each of the spikes 160 is covered by a spike cap 63, which may beremoved, exposing the respective spike and allowing connection to arespective line 30. As described above, the lines 30 may be attached toone or more solution containers or other sources of material, e.g., foruse in dialysis and/or the formulation of dialysate, or connected to oneor more collection bags for sampling purposes or for peritonealequilibration testing (PET test).

FIGS. 3 and 4 show exploded views (perspective and top views,respectively) of the cassette 24 in this illustrative embodiment. Thecassette 24 is formed as a relatively thin and flat member having agenerally planar shape, e.g., may include components that are molded,extruded or otherwise formed from a suitable plastic. In thisembodiment, the cassette 24 includes a base member 18 that functions asa frame or structural member for the cassette 24 as well as forming, atleast in part, various flow channels, ports, valve portions, etc. Thebase member 18 may be molded or otherwise formed from a suitable plasticor other material, such as a polymethyl methacrylate (PMMA) acrylic, ora cyclic olefin copolymer/ultra low density polyethylene (COC/ULDPE),and may be relatively rigid. In an embodiment, the ratio of COC to ULDPEcan be approximately 85%/15%. FIG. 3 also shows the ports for the heaterbag (port 150), drain (port 152) and the patient (port 154) that areformed in the base member 18. Each of these ports may be arranged in anysuitable way, such as, for example, a central tube 156 extending from anouter ring or skirt 158, or a central tube alone. Flexible tubing foreach of the heater bag, drain and patient lines 26, 28, 34 may beconnected to the central tube 156 and engaged by the outer ring 158, ifpresent.

Both sides of the base member 18 may be covered, at least in part, by amembrane 15 and 16, e.g., a flexible polymer film made from, forexample, polyvinyl chloride (PVC), that is cast, extruded or otherwiseformed. Alternatively, the sheet may be formed as a laminate of two ormore layers of poly-cyclohexylene dimethylene cyclohexanedicarboxylate(PCCE) and/or ULDPE, held together, for example, by a coextrudableadhesive (CXA). In some embodiments, the membrane thickness may be inthe range of approximately 0.002 to 0.020 inches thick. In a preferredembodiment, the thickness of a PVC—based membrane may be in the range ofapproximately 0.012 to 0.016 inches thick, and more preferablyapproximately 0.014 inches thick. In another preferred embodiment, suchas, for example, for laminate sheets, the thickness of the laminate maybe in the range of approximately 0.006 to 0.010 inches thick, and morepreferably approximately 0.008 inches thick.

Both membranes 15 and 16 may function not only to close or otherwiseform a part of flowpaths of the cassette 24, but also may be moved orotherwise manipulated to open/close valve ports and/or to function aspart of a pump diaphragm, septum or wall that moves fluid in thecassette 24. For example, the membranes 15 and 16 may be positioned onthe base member 18 and sealed (e.g., by heat, adhesive, ultrasonicwelding or other means) to a rim around the periphery of the base member18 to prevent fluid from leaking from the cassette 24. The membrane 15may also be bonded to other, inner walls of the base member 18, e.g.,those that form various channels, or may be pressed into sealing contactwith the walls and other features of the base member 18 when thecassette 24 suitably mounted in the cycler 14. Thus, both of themembranes 15 and 16 may be sealed to a peripheral rim of the base member18, e.g., to help prevent leaking of fluid from the cassette 24 upon itsremoval from the cycler 14 after use, yet be arranged to lie,unattached, over other portions of the base member 18. Once placed inthe cycler 14, the cassette 24 may be squeezed between opposed gasketsor other members so that the membranes 15 and 16 are pressed intosealing contact with the base member 18 at regions inside of theperiphery, thereby suitably sealing channels, valve ports, etc., fromeach other.

Other arrangements for the membranes 15 and 16 are possible. Forexample, the membrane 16 may be formed by a rigid sheet of material thatis bonded or otherwise made integral with the body 18. Thus, themembrane 16 need not necessarily be, or include, a flexible member.Similarly, the membrane 15 need not be flexible over its entire surface,but instead may include one or more flexible portions to permit pumpand/or valve operation, and one or more rigid portions, e.g., to closeflowpaths of the cassette 24. It is also possible that the cassette 24may not include the membrane 16 or the membrane 15, e.g., where thecycler 14 includes a suitable member to seal pathways of the cassette,control valve and pump function, etc.

In accordance with another aspect of the invention, the membrane 15 mayinclude a pump chamber portion 151 (“pump membrane”) that is formed tohave a shape that closely conforms to the shape of a corresponding pumpchamber 181 depression in the base 18. For example, the membrane 15 maybe generally formed as a flat member with thermoformed (or otherwiseformed) dome-like shapes 151 that conform to the pump chamberdepressions of the base member 18. The dome-like shape of the pre-formedpump chamber portions 151 may be constructed, for example, by heatingand forming the membrane over a vacuum form mold of the type shown inFIG. 5. As shown in FIG. 5, the vacuum may be applied through acollection of holes along the wall of the mold. Alternatively, the wallof the mold can be constructed of a porous gas-permeable material, whichmay result in a more uniformly smooth surface of the molded membrane. Inone example, the molded membrane sheet 15 is trimmed while attached tothe vacuum form mold. The vacuum form mold then presses the trimmedmembrane sheet 15 against the cassette body 18 and bonds them together.In one embodiment the membrane sheets 15,16 are heat-welded to thecassette body 18. In this way, the membrane 15 may move relative to thepump chambers 181 to effect pumping action without requiring stretchingof the membrane 15 (or at least minimal stretching of the membrane 15),both when the membrane 15 is moved maximally into the pump chambers 181and (potentially) into contact with spacer elements 50 (e.g., as shownin solid line in FIG. 4 while pumping fluid out of the pump chamber181), and when the membrane 15 is maximally withdrawn from the pumpchamber 181 (e.g., as shown in dashed line in FIG. 4 when drawing fluidinto the pump chamber 181). Avoiding stretching of the membrane 15 mayhelp prevent pressure surges or other changes in fluid delivery pressuredue to sheet stretch and/or help simplify control of the pump whenseeking to minimize pressure variation during pump operation. Otherbenefits may be found, including reduced likelihood of membrane 15failure (e.g., due to tears in the membrane 15 resulting from stressesplace on the membrane 15 during stretching), and/or improved accuracy inpump delivery volume measurement, as described in more detail below. Inone embodiment, the pump chamber portions 151 may be formed to have asize (e.g., a define a volume) that is about 85-110% of the pump chamber181, e.g., if the pump chamber portions 151 define a volume that isabout 100% of the pump chamber volume, the pump chamber portion 151 maylie in the pump chamber 181 and in contact with the spacers 50 while atrest and without being stressed.

Providing greater control of the pressure used to generate a fill anddelivery stroke of liquid into and out of a pump chamber may haveseveral advantages. For example, it may be desirable to apply theminimum negative pressure possible when the pump chamber draws fluidfrom the patient's peritoneal cavity during a drain cycle. A patient mayexperience discomfort during the drain cycle of a treatment in partbecause of the negative pressure being applied by the pumps during afill stroke. The added control that a pre-formed membrane can provide tothe negative pressure being applied during a fill stroke may help toreduce the patient's discomfort.

A number of other benefits may be realized by using pump membranespre-formed to the contour of the cassette pump chamber. For example, theflow rate of liquid through the pump chamber can be made more uniform,because a constant pressure or vacuum can be applied throughout the pumpstroke, which in turn may simplify the process of regulating the heatingof the liquid. Moreover, temperature changes in the cassette pump mayhave a smaller effect on the dynamics of displacing the membrane, aswell as the accuracy of measuring pressures within the pump chambers. Inaddition, pressure spikes within the fluid lines can be minimized. Also,correlating the pressures measured by pressure transducers on thecontrol (e.g. pneumatic) side of the membrane with the actual pressureof the liquid on the pump chamber side of the membrane may be simpler.This in turn may permit more accurate head height measurements of thepatient and fluid source bags prior to therapy, improve the sensitivityof detecting air in the pump chamber, and improve the accuracy ofvolumetric measurements. Furthermore, eliminating the need to stretchthe membrane may allow for the construction and use of pump chambershaving greater volumes.

In this embodiment, the cassette 24 includes a pair of pump chambers 181that are formed in the base member 18, although one pump chamber or morethan two pump chambers are possible. In accordance with an aspect of theinvention, the inner wall of pump chambers 181 includes spacer elements50 that are spaced from each other and extend from the inner wall ofpump chamber 18 to help prevent portions of the membrane 15 fromcontacting the inner wall of pump chamber 181. (As shown on theright-side pump chamber 181 in FIG. 4, the inner wall is defined by sideportions 181 a and a bottom portion 181 b. The spacers 50 extendupwardly from the bottom portion 181 b in this embodiment, but couldextend from the side portions 181 a or be formed in other ways.) Bypreventing contact of the membrane 15 with the pump chamber inner wall,the spacer elements 50 may provide a dead space (or trap volume) whichmay help trap air or other gas in the pump chamber 181 and inhibit thegas from being pumped out of the pump chamber 181 in some circumstances.In other cases, the spacers 50 may help the gas move to an outlet of thepump chamber 181 so that the gas may be removed from the pump chamber181, e.g., during priming. Also, the spacers 50 may help prevent themembrane 15 from sticking to the pump chamber inner wall and/or allowflow to continue through the pump chamber 181, even if the membrane 15is pressed into contact with the spacer elements 50. In addition, thespacers 50 help to prevent premature closure of the outlet port of thepump chamber (openings 187 and/or 191) if the sheet happens to contactthe pump chamber inner wall in a non-uniform manner. Further detailsregarding the arrangement and/or function of spacers 50 are provided inU.S. Pat. Nos. 6,302,653 and 6,382,923, both of which are incorporatedherein by reference.

In this embodiment, the spacer elements 50 are arranged in a kind of“stadium seating” arrangement such that the spacer elements 50 arearranged in a concentric elliptical pattern with ends of the spacerelements 50 increasing in height from the bottom portion 181 b of theinner wall with distance away from the center of the pump chamber 181 toform a semi-elliptical domed shaped region (shown by dotted line in FIG.4). Positioning spacer elements 50 such that the ends of the spacerelements 50 form a semi-elliptical region that defines the domed regionintended to be swept by the pump chamber portion 151 of the membrane 15may allow for a desired volume of dead space that minimizes anyreduction to the intended stroke capacity of pump chambers 181. As canbe seen in FIG. 3 (and FIG. 6), the “stadium seating” arrangement inwhich spacer elements 50 are arranged may include “aisles” or breaks 50a in the elliptical pattern. Breaks (or aisles) 50 a help to maintain anequal gas level throughout the rows (voids or dead space) 50 b betweenspacer elements 50 as fluid is delivered from the pump chamber 181. Forexample, if the spacer elements 50 were arranged in the stadium seatingarrangement shown in FIG. 6 without breaks (or aisles) 50 a or othermeans of allowing liquid and air to flow between spacer elements 50, themembrane 15 might bottom out on the spacer element 50 located at theoutermost periphery of the pump chamber 181, trapping whatever gas orliquid is present in the void between this outermost spacer element 50and the side portions 181 a of the pump chamber wall. Similarly, if themembrane 15 bottomed out on any two adjacent spacer elements 50, any gasand liquid in the void between the elements 50 may become trapped. Insuch an arrangement, at the end of the pump stroke, air or other gas atthe center of pump chamber 181 could be delivered while liquid remainsin the outer rows. Supplying breaks (or aisles) 50 a or other means offluidic communication between the voids between spacer elements 50 helpsto maintain an equal gas level throughout the voids during the pumpstroke, such that air or other gas may be inhibited from leaving thepump chamber 181 unless the liquid volume has been substantiallydelivered.

In certain embodiments, spacer elements 50 and/or the membrane 15 may bearranged so that the membrane 15 generally does not wrap or otherwisedeform around individual spacers 50 when pressed into contact with them,or otherwise extend significantly into the voids between spacers 50.Such an arrangement may lessen any stretching or damage to membrane 15caused by wrapping or otherwise deforming around one or more individualspacer elements 50. For example, it has also been found to beadvantageous in this embodiment to make the size of the voids betweenspacers 50 approximately equal in width to the width of the spacers 50.This feature has shown to help prevent deformation of the membrane 15,e.g., sagging of the membrane into the voids between spacers 50, whenthe membrane 15 is forced into contact with the spacers 50 during apumping operation.

In accordance with another aspect of the invention, the inner wall ofpump chambers 181 may define a depression that is larger than the space,for example a semi-elliptical or domed space, intended to be swept bythe pump chamber portion 151 of the membrane 15. In such instances, oneor more spacer elements 50 may be positioned below the domed regionintended to be swept by the membrane portion 151 rather than extendinginto that domed region. In certain instances, the ends of spacerelements 50 may define the periphery of the domed region intended to beswept by the membrane 15. Positioning spacer elements 50 outside of, oradjacent to, the periphery of the domed region intended to be swept bythe membrane portion 151 may have a number of advantages. For example,positioning one or more spacer elements 50 such that the spacer elementsare outside of, or adjacent to, the domed region intended to be swept bythe flexible membrane provides a dead space between the spacers and themembrane, such as described above, while minimizing any reduction to theintended stroke capacity of pump chambers 181.

It should be understood that the spacer elements 50, if present, in apump chamber may be arranged in any other suitable way, such as forexample, shown in FIG. 7. The left side pump chamber 181 in FIG. 7includes spacers 50 arranged similarly to that in FIG. 6, but there isonly one break or aisle 50 a that runs vertically through theapproximate center of the pump chamber 181. The spacers 50 may bearranged to define a concave shape similar to that in FIG. 6 (i.e., thetops of the spacers 50 may form the semi-elliptical shape shown in FIGS.3 and 4), or may be arranged in other suitable ways, such as to form aspherical shape, a box-like shape, and so on. The right-side pumpchamber 181 in FIG. 7 shows an embodiment in which the spacers 50 arearranged vertically with voids 50 b between spacers 50 also arrangedvertically. As with the left-side pump chamber, the spacers 50 in theright-side pump chamber 181 may define a semi-elliptical, spherical,box-like or any other suitably shaped depression. It should beunderstood, however, that the spacer elements 50 may have a fixedheight, a different spatial pattern that those shown, and so on.

Also, the membrane 15 may itself have spacer elements or other features,such as ribs, bumps, tabs, grooves, channels, etc., in addition to, orin place of the spacer elements 50. Such features on the membrane 15 mayhelp prevent sticking of the membrane 15, etc., and/or provide otherfeatures, such as helping to control how the sheet folds or otherwisedeforms when moving during pumping action. For example, bumps or otherfeatures on the membrane 15 may help the sheet to deform consistentlyand avoid folding at the same area(s) during repeated cycles. Folding ofa same area of the membrane 15 at repeated cycles may cause the membrane15 to prematurely fail at the fold area, and thus features on themembrane 15 may help control the way in which folds occur and where.

In this illustrative embodiment, the base member 18 of the cassette 24defines a plurality of controllable valve features, fluid pathways andother structures to guide the movement of fluid in the cassette 24. FIG.6 shows a plan view of the pump chamber side of the base member 18,which is also seen in perspective view in FIG. 3. FIG. 8 shows aperspective view of a back side of the base member 18, and FIG. 9 showsa plan view of the back side of the base member 18. The tube 156 foreach of the ports 150, 152 and 154 fluidly communicates with arespective valve well 183 that is formed in the base member 18. Thevalve wells 183 are fluidly isolated from each other by wallssurrounding each valve well 183 and by sealing engagement of themembrane 15 with the walls around the wells 183. As mentioned above, themembrane 15 may sealingly engage the walls around each valve well 183(and other walls of the base member 18) by being pressed into contactwith the walls, e.g., when loaded into the cycler 14. Fluid in the valvewells 183 may flow into a respective valve port 184, if the membrane 15is not pressed into sealing engagement with the valve port 184. Thus,each valve port 184 defines a valve (e.g., a “volcano valve”) that canbe opened and closed by selectively moving a portion of the membrane 15associated with the valve port 184. As will be described in more detailbelow, the cycler 14 may selectively control the position of portions ofthe membrane 15 so that valve ports (such as ports 184) may be opened orclosed so as to control flow through the various fluid channels andother pathways in the cassette 24. Flow through the valve ports 184leads to the back side of the base member 18. For the valve ports 184associated with the heater bag and the drain (ports 150 and 152), thevalve ports 184 lead to a common channel 200 formed at the back side ofthe base member 18. As with the valve wells 183, the channel 200 isisolated from other channels and pathways of the cassette 24 by thesheet 16 making sealing contact with the walls of the base member 18that form the channel 200. For the valve port 184 associated with thepatient line port 154, flow through the port 184 leads to a commonchannel 202 on the back side of the base member 18.

Returning to FIG. 6, each of the spikes 160 (shown uncapped in FIG. 6)fluidly communicates with a respective valve well 185, which areisolated from each other by walls and sealing engagement of the membrane15 with the walls that form the wells 185. Fluid in the valve wells 185may flow into a respective valve port 186, if the membrane 15 is not insealing engagement with the port 186. (Again, the position of portionsof the membrane 15 over each valve port 186 can be controlled by thecycler 14 to open and close the valve ports 186.) Flow through the valveports 186 leads to the back side of the base member 18 and into thecommon channel 202. Thus, in accordance with one aspect of theinvention, a cassette may have a plurality of solution supply lines (orother lines that provide materials for providing dialysate) that areconnected to a common manifold or channel of the cassette, and each linemay have a corresponding valve to control flow from/to the line withrespect to the common manifold or channel. Fluid in the channel 202 mayflow into lower openings 187 of the pump chambers 181 by way of openings188 that lead to lower pump valve wells 189 (see FIG. 6). Flow from thelower pump valve wells 189 may pass through a respective lower pumpvalve port 190 if a respective portion of the membrane 15 is not pressedin sealing engagement with the port 190. As can be seen in FIG. 9, thelower pump valve ports 190 lead to a channel that communicates with thelower openings 187 of the pump chambers 181. Flow out of the pumpchambers 181 may pass through the upper openings 191 and into a channelthat communicates with an upper valve port 192. Flow from the uppervalve port 192 (if the membrane 15 is not in sealing engagement with theport 192) may pass into a respective upper valve well 194 and into anopening 193 that communicates with the common channel 200 on the backside of the base member 18.

As will be appreciated, the cassette 24 may be controlled so that thepump chambers 181 can pump fluid from and/or into any of the ports 150,152 and 154 and/or any of the spikes 160. For example, fresh dialysateprovided by one of the containers 20 that is connected by a line 30 toone of the spikes 160 may be drawn into the common channel 202 byopening the appropriate valve port 186 for the proper spike 160 (andpossibly closing other valve ports 186 for other spikes). Also, thelower pump valve ports 190 may be opened and the upper pump valve ports192 may be closed. Thereafter, the portion of the membrane 15 associatedwith the pump chambers 181 (i.e., pump membranes 151) may be moved(e.g., away from the base member 18 and the pump chamber inner wall) soas to lower the pressure in the pump chambers 181, thereby drawing fluidin through the selected spike 160 through the corresponding valve port186, into the common channel 202, through the openings 188 and into thelower pump valve wells 189, through the (open) lower pump valve ports190 and into the pump chambers 181 through the lower openings 187. Thevalve ports 186 are independently operable, allowing for the option todraw fluid through any one or a combination of spikes 160 and associatedsource containers 20, in any desired sequence, or simultaneously. (Ofcourse, only one pump chamber 181 need be operable to draw fluid intoitself. The other pump chamber may be left inoperable and closed off toflow by closing the appropriate lower pump valve port 190.)

With fluid in the pump chambers 181, the lower pump valve ports 190 maybe closed, and the upper pump valve ports 192 opened. When the membrane15 is moved toward the base member 18, the pressure in the pump chambers181 may rise, causing fluid in the pump chambers 181 to pass through theupper openings 191, through the (open) upper pump valve ports 192 andinto the upper pump valve wells 194, through the openings 193 and intothe common channel 200. Fluid in the channel 200 may be routed to theheater bag port 150 and/or the drain port 152 (and into thecorresponding heater bag line or drain line) by opening the appropriatevalve port 184. In this way, for example, fluid in one or more of thecontainers 20 may be drawn into the cassette 24, and pumped out to theheater bag 22 and/or the drain.

Fluid in the heater bag 22 (e.g., after having been suitably heated onthe heater tray for introduction into the patient) may be drawn into thecassette 24 by opening the valve port 184 for the heater bag port 150,closing the lower pump valve ports 190, and opening the upper pump valveports 192. By moving the portions of the membrane 15 associated with thepump chambers 181 away from the base member 18, the pressure in the pumpchambers 181 may be lowered, causing fluid flow from the heater bag 22and into the pump chambers 181. With the pump chambers 181 filled withheated fluid from the heater bag 22, the upper pump valve ports 192 maybe closed and the lower pump valve ports 190 opened. To route the heateddialysate to the patient, the valve port 184 for the patient port 154may be opened and valve ports 186 for the spikes 160 closed. Movement ofthe membrane 15 in the pump chambers 181 toward the base member 18 mayraise the pressure in the pump chambers 181 causing fluid to flowthrough the lower pump valve ports 190, through the openings 188 andinto the common channel 202 to, and through, the (open) valve port 184for the patient port 154. This operation may be repeated a suitablenumber of times to transfer a desired volume of heated dialysate to thepatient.

When draining the patient, the valve port 184 for the patient port 154may be opened, the upper pump valve ports 192 closed, and the lower pumpvalve ports 190 opened (with the spike valve ports 186 closed). Themembrane 15 may be moved to draw fluid from the patient port 154 andinto the pump chambers 181. Thereafter, the lower pump valve ports 190may be closed, the upper valve ports 192 opened, and the valve port 184for the drain port 152 opened. Fluid from the pump chambers 181 may thenbe pumped into the drain line for disposal or for sampling into a drainor collection container. (Alternatively, fluid may also be routed to oneor more spikes 160/lines 30 for sampling or drain purposes). Thisoperation may be repeated until sufficient dialysate is removed from thepatient and pumped to the drain.

The heater bag 22 may also serve as a mixing container. Depending on thespecific treatment requirements for an individual patient, dialysate orother solutions having different compositions can be connected to thecassette 24 via suitable solution lines 30 and spikes 160. Measuredquantities of each solution can be added to heater bag 22 using cassette24, and admixed according to one or more pre-determined formulae storedin microprocessor memory and accessible by control system 16.Alternatively, specific treatment parameters can be entered by the uservia user interface 144. The control system 16 can be programmed tocompute the proper admixture requirements based on the type of dialysateor solution containers connected to spikes 160, and can then control theadmixture and delivery of the prescribed mixture to the patient.

In accordance with an aspect of the invention, the pressure applied bythe pumps to dialysate that is infused into the patient or removed fromthe patient may be controlled so that patient sensations of “tugging” or“pulling” resulting from pressure variations during drain and filloperations may be minimized. For example, when draining dialysate, thesuction pressure (or vacuum/negative pressure) may be reduced near theend of the drain process, thereby minimizing patient sensation ofdialysate removal. A similar approach may be used when nearing the endof a fill operation, i.e., the delivery pressure (or positive pressure)may be reduced near the end of fill. Different pressure profiles may beused for different fill and/or drain cycles in case the patient is foundto be more or less sensitive to fluid movement during different cyclesof the therapy. For example, a relatively higher (or lower) pressure maybe used during fill and/or drain cycles when a patient is asleep, ascompared to when the patient is awake. The cycler 14 may detect thepatient's sleep/awake state, e.g., using an infrared motion detector andinferring sleep if patient motion is reduced, or using a detected changein blood pressure, brain waves, or other parameter that is indicative ofsleep, and so on. Alternately, the cycler 14 may simply “ask” thepatient—“are you asleep?” and control system operation based on thepatient's response (or lack of response).

Patient Line State Detection Apparatus

In one aspect, a patient line state detector detects when a fluid lineto a patient, such as patient line 34, is adequately primed with fluidbefore it is connected to the patient. (It should be understood thatalthough a patient line state detector is described in connection with apatient line, aspects of the invention include the detection of thepresence any suitable tubing segment or other conduit and/or a fillstate of the tubing segment or other conduit. Thus, aspects of theinvention are not limited to use with a patient line, as a tubing statedetector may be used with any suitable conduit.) In some embodiments, apatient line state detector can be used to detect adequate priming of atubing segment of the patient-connecting end of a fluid line. Thepatient line 34 may be connected to an indwelling catheter in apatient's blood vessel, in a body cavity, subcutaneously, or in anotherorgan. In one embodiment, the patient line 34 may be a component of aperitoneal dialysis system 10, delivering dialysate to and receivingfluid from a patient's peritoneal cavity. A tubing segment near thedistal end of the line may be placed in an upright position in a cradlewithin which the sensor elements of the detector are located. FIG. 9-1Ashows a front perspective view of an exemplary configuration of apatient line state detector 1000, which may be mounted on, or otherwiseexposed at, the left side exterior of the housing 82, e.g., to the leftof the front door 141. The patient line 34 should preferably be primedprior to being connected to the patient, because air could otherwise bedelivered into the patient, raising the risk of complications. It may bepermissible in some settings to allow up to 1 mL of air to be present inthe patient line 34 prior to being connected to a patient's peritonealdialysis catheter. The exemplary configurations of the patient linestate detector 1000 described below will generally meet or exceed thisstandard, as they are capable of detecting a liquid level in a properlypositioned tubing segment of line 34 so that at most about 0.2 mL of airremains in the distal end of line 34 after priming.

In one aspect, a first configuration patient line state detector 1000may include a base member 1002. There may also be a patient line statedetector housing 1006 affixed to (or co-molded with) the base member1002, such that the detector housing 1006 may extend outwardly from thebase member 1002. The detector housing 1006 defines a tube or connectorholding channel 1012 within which a tubing segment 34 a near the distalend of a patient line 34, or its associated connector 36 may bepositioned. The portion of the detector housing 1006 facing the basemember 1002 may be substantially hollow, and as a result an open cavity1008 (shown in FIG. 9-3) may be created behind the detector housing1006. The open cavity 1008 may accommodate the placement and positioningof sensor elements (1026, 1028, 1030 and 1032 shown in FIG. 9-3) next tothe channel 1012 within which tubing segment 34 a may be positioned. Inan alternative embodiment, there may also optionally be a stabilizingtab 1010 extending outwardly from the base member 1002. The stabilizingtab 1010 may have a concave outer shape, so that it may substantiallyconform to the curvature of the patient line connector 36 when thepatient line 34 is placed in the patient line state detector housing1006. The stabilizing tab 1010 may help to prevent the connector 36 frommoving during priming of the patient line 34, increasing the accuracyand efficiency of the priming process. The detector housing 1006 mayhave a shape that generally helps to define the tube or connectorholding channel 1012, which in turn may have dimensions that vary toaccommodate the transition from tubing segment 34 a to tube connector36.

In this illustrative embodiment, the channel 1012 may substantiallyconform to the shape of the patient line connector 36. As a result thechannel 1012 may be “U-shaped” so as to encompass a portion of theconnector 36 when it is placed into the channel 1012. The channel 1012may be made up of two distinct features; a tube portion 1014 and acradle 1016. In another aspect, the tube portion 1014 may be positionedbelow the cradle 1016. Additionally, the cradle 1016 may be formed by apair of side walls 1018 and a back wall 1020. Both of the side walls1018 may be slightly convex in shape, while the back wall 1020 may begenerally flat or otherwise may have a contour generally matching theshape of the adjacent portion of connector 36. A generally convex shapeof the side walls 1018 helps to lock the patient line connector 36 intoplace when positioned in the cradle 1016.

In an illustrative embodiment for a first configuration of patient linestate detector 1000, a region 36 a of the patient line connector 36 mayhave a generally planar surface that can rest securely against theopposing back wall 1020 of channel 1012. Additionally, this region 36 aof the connector 36 may have recesses 37 on opposing sides, which can bepositioned adjacent to the opposing side walls 1018 of channel 1012 whenthe connector 36 is positioned within the detector housing 1006. Therecesses 37 can be defined by flanking raised elements 37 a of connector36. One of these recesses 37 is partially visible in FIG. 9-1. The twoside walls 1018 may have a generally mating shape (such as, e.g. aconvex shape) to engage recesses 37 and to help lock connector 36 intoplace within cradle 1016. This helps to prevent the connector 36 andtubing segment 34 a from being inadvertently removed from the detectorhousing 1006 during priming of the patient line 34. If the raisedelements 37 a of connector 36 are made of sufficiently flexible material(such as, e.g., polypropylene, polyethylene, or other similarpolymer-based material) a threshold pulling force against connector 36will be capable of disengaging connector 36 and tubing segment 34 a fromthe detector housing 1006.

In another aspect, the tube portion 1014 of the cavity 1012 may surrounda majority of tubing segment 34 a at a point just before tubing segment34 a attaches to the connector 36. The tube portion 1014 may contain amajority of tubing segment 34 a using three structures: the two sidewalls 1018 and the back wall 1020. In an embodiment, the two side walls1018 and back wall 1020 may be transparent or sufficiently translucent(constructed from, e.g. plexiglass) so as to allow the light from aplurality of LED's (such as, e.g., LED's 1028, 1030, and 1032 in FIG.9-3) to be directed through the walls without being significantlyblocked or diffused. An optical sensor 1026 (shown in FIG. 9-2), mayalso be positioned along one of the walls 1018, and can detect the lightbeing emitted by the LED's. In the illustrated embodiment, a transparentor translucent plastic insert 1019 may be constructed to snap into themain detector housing 1006 in the region where the LED's have beenpositioned in the housing.

FIG. 9-2 shows a perspective layout view with LED's 1028, 1030, and 1032and optical sensor 1026 surface-mounted on a patient line state detectorprinted circuit board 1022. FIG. 9-3 shows a plan view of LED's 1028,1030, and 1032 and optical sensor 1026 mounted on detector circuit board1022, where the detector circuit board 1022 can be positioned adjacentthe back wall 1020 and side walls 1018 of detector housing 1006. FIG.9-4 is an exploded perspective view of detection assembly 1000 showingthe relative positions of the printed circuit board 1022 and thetranslucent or transparent plastic insert 1019 with respect to thehousing 1006.

Referring also to the illustrative embodiment of FIG. 9-1B, the detectorcircuit board 1022 may be positioned on a support structure 1004 andinside open cavity 1008, which was formed from detector housing 1006extending outwardly from base member 1002. The base member 1002 andsupport structure 1004 may be affixed to one another, or may beco-molded, so that the base member 1002 is generally perpendicular tothe support structure 1004. This orientation generally permits the planeof the detector circuit board 1022 to be generally perpendicular to thelong axis of tubing segment 34 a when secured within channel 1012. Thedetector circuit board 1022 may conform generally to the cross-sectionalshape of open cavity 1008, and it may also include a cutout 1024 (FIG.9-2, 9-3) generally matching the cross-sectional shape of channel 1012formed by back wall 1020 and side walls 1018 (FIG. 9-1A). The detectorcircuit board 1022 may then be positioned within open cavity 1008 withcutout 1024 nearly adjacent to side walls 1018 and back wall 1020 ofdetector housing 1006 in order to ensure proper alignment of thedetector circuit board 1022 with tubing segment 34 a or connector 36.

The detector circuit board 1022 may include a plurality of LED's and atleast one optical sensor, which may be attached to circuit board 1022,and in one embodiment, the LED's and optical sensor may besurface-mounted to circuit board 1022. In one aspect, the detectorcircuit board 1022 may include a first LED 1028, a second LED 1030, athird LED 1032, and an optical sensor 1026. A first LED 1028 and asecond LED 1030 may be positioned so as to direct light through the sameside wall 1018 a of channel 1012. The light emitted by the first LED1028 and the second LED 1030 may be directed in a generally paralleldirection, generally perpendicular to the side wall 1018 a to which theyare nearest. An optical sensor 1026 may be positioned along the oppositeside wall 1018 b of channel 1012. Furthermore, a third LED 1032 may bepositioned along the back wall 1020 of channel 1012. In thisillustrative embodiment, such a configuration of the LED's and theoptical sensor 1026 allows the patient line state detector 1000 todetect three different states during the course of priming the patientline 34; a tubing segment 34 a or connector 36 nearly completely filledwith fluid (primed state), an incompletely filled tubing segment 34 a orconnector 36 (non-primed state), or the absence of a tubing segment 34 aand/or connector 36 from channel 1012 (line-absent state).

When used in a peritoneal dialysis system such as, for exampleperitoneal dialysis system 10, configuring the detector circuit board1022 in this fashion allows the appropriate control signal to be sent tothe PD cycler controller system 16. Controller system 16 may then informthe user, via user interface 144, to position the distal end of line 34in the patient line state detector 1000 prior to making a connection tothe peritoneal dialysis catheter. The controller may then monitor forplacement of tubing segment 34 a within patient line state detector1000. The controller may then proceed to direct the priming of line 34,to direct termination of priming once line 34 is primed, and then toinstruct the user to disengage the distal end of line 34 from thepatient line state detector 1000 and connect it to the user's peritonealdialysis catheter.

Surface mounting the LED's 1028, 1030, and 1032 and the optical sensor1026 to the circuit board 1022 can simplify manufacturing processes forthe device, can allow the patient line state detector 1000 and circuitboard 1022 to occupy a relatively small amount of space, and can helpeliminate errors that may arise from movement of the LED's or theoptical sensor relative to each other or to the channel 1012. Were itnot for surface mounting of the sensor components, misalignment of thecomponents could occur either during assembly of the device, or duringits use.

In one aspect, the optical axis (or central optical axis) of LED 1032may form an oblique angle with the optical axis of optical sensor 1026.In the illustrated embodiment, the optical axis of a first LED 1028, asecond LED 1030, and an optical sensor 1026 are each generally parallelto each other and to back wall 1020 of channel 1012. Thus, the amount oflight directed toward optical sensor 1026 from the LED's may varydepending on the presence or absence of (a) a translucent or transparentconduit within channel 1012 and/or (b) the presence of liquid within theconduit (which, for example, may be tubing segment 34 a). Preferably,LED 1032 may be positioned near the side wall (e.g., 1018 a) that isfarthest from optical sensor 1026 in order for some of the light emittedby LED 1032 to be refracted by the presence of a translucent ortransparent tubing segment 34 a within channel 1012. The degree ofrefraction away from or toward optical sensor 1026 may depend on thepresence or absence of fluid in tubing segment 34 a.

In various embodiments, the oblique angle of LED 1032 with respect tooptical sensor 1026 creates a more robust system for determining thepresence or absence of liquid with a translucent or transparent conduitin channel 1012. LED 1032 may be positioned so that its optical axis canform any angle between 91° and 179° with respect to the optical axis ofoptical sensor 1026. Preferably the angle may be set within the range ofabout 95° to about 135° with respect to the optical sensor's opticalaxis. More preferably, LED 1032 may be set to have an optical axis ofabout 115°+/−5° with respect to the optical axis of optical sensor 1026.In an illustrative embodiment shown in FIG. 9-3, the angle θ of theoptical axis of LED 1032 with respect to the optical axis of opticalsensor 1026 was set to approximately 115°, +/−5°. (The optical axis ofoptical sensor 1026 in this particular embodiment is roughly parallel toback wall 1020, and roughly perpendicular to side wall 1018 b). Theadvantage of angling LED 1032 with respect to the optical axis ofoptical sensor 1026 was confirmed in a series of tests comparing theperformance of the optical sensor 1026 in distinguishing a fluid filledtube segment (wet tube) from an air filled tube segment (dry tube) usingan LED 1032 oriented at about a 115° angle vs. an LED whose optical axiswas directed either perpendicularly or parallel to the optical axis ofoptical sensor 1026. The results showed that an angled LED-based systemwas more robust in distinguishing the presence or absence of liquid intubing segment 34 a. Using an angled LED 1032, it was possible to selectan optical sensor signal strength threshold above which an empty tubingsegment 34 a could reliably be detected. It was also possible to selectan optical sensor signal strength threshold below which a liquid-filledtubing segment 34 a could reliably be detected.

FIG. 9-12 shows a graph of test results demonstrating the ability ofpatient line state detector 1000 to distinguish between a liquid-filledtubing segment 34 a (primed state) and an empty tubing segment 34 a(non-primed state). The results were recorded with LED 1032 (third LED)oriented at an angle of about 115° with respect to the optical axis ofoptical sensor 1026, and LED 1030 (second LED) oriented roughly parallelto the optical axis of optical sensor 1026. The results plotted in FIG.9-12 demonstrate that patient line state detector 1000 can reliablydiscriminate between a primed state and a non-primed state. When therelative signal strength associated with light received from LED 1030was approximately 0.4 or above, it was possible to resolve an uppersignal detection threshold 1027 and a lower signal detection threshold1029 for a non-primed vs. primed state using only the light signalreceived from LED 1032. The upper threshold 1027 can be used to identifythe non-primed state, and the lower threshold 1029 can be used toidentify the primed state. The data points located above theupper-threshold 1027 are associated with an empty tubing segment 34 a(non-primed state), and the data points located below thelower-threshold 1029 are associated with a liquid-filled tubing segment34 a (primed state). A relatively narrow region 1031 between these twothreshold values defines a band of relative signal strength associatedwith light received from LED 1032 in which an assessment of the primingstate of tubing segment 34 a may be indeterminate. A controller (suchas, e.g., control system 16) may be programmed to send the user anappropriate message whenever a signal strength associated with lightreceived from LED 1032 falls within this indeterminate range. Forexample, the user may be instructed to assess whether tubing segment 34a and/or connector 36 are properly mounted in patient line statedetector 1000. In the context of a peritoneal dialysis system, ifoptical sensor 1026 generates a signal corresponding with an emptytubing segment 34 a, the controller can direct the cycler to continue toprime patient line 34 with dialysate. A signal corresponding to aliquid-filled tubing segment 34 a can be used by the controller to stopfurther priming and instruct the user that the fluid line 34 is ready tobe connected to a dialysis catheter.

In an embodiment, the cycler controller may continuously monitor thereceived signal from one of the LED's at the initiation of the primingprocedure. Upon detection of a change in the received signal, thecontroller may halt further fluid pumping to carry out a fullmeasurement using all of the LED's. If the received signals are wellwithin the range indicating a wet tube, then further priming may behalted. However, if the received signals are within the indeterminateregion 1031 or within the ‘dry’ region, then the cycler may command aseries of small incremental pulses of fluid into the patient line by thepumping cassette, with a repeat reading of the LED signal strengthsafter each pulse of fluid. The priming can then be halted as soon as areading is achieved that indicates a fluid-filled line at the level ofthe sensor. Incremental pulses of fluid may be accomplished bycommanding brief pulses of the valve connecting the pressure reservoirto the pump actuation or control chamber. Alternatively, the controllermay command the application of continuous pressure to the pump actuationor control chamber, and command the pump's outlet valve to open brieflyand close to generate the series of fluid pulses.

FIG. 9-13 shows a graph of test results demonstrating the superiority ofan angled LED 1032 (LEDc) when compared with an LED (LEDd) whose opticalaxis is roughly perpendicular to the optical axis of optical sensor1026. In this case, the relative signal strength generated by opticalsensor 1026 in response to light from LEDc was plotted against thesignal strength associated with light from LEDd. Although someseparation between a liquid-filled (‘primed’) and empty (‘non-primed’)tubing segment 34 a was apparent at an LEDd relative signal strength ofabout 0.015, there remained a substantial number of ‘non-primed’ datapoints 1035 that cannot be distinguished from ‘primed’ data points basedon this threshold value. On the other hand, a relative signal strength1033 associated with light from LEDc of 0.028-0.03 can effectivelydiscriminate between ‘primed’ tubing segment 34 a (primed state) and‘non-primed’ tubing segment 34 a (non-primed state). Thus an angled LED(1032) can generate more reliable data than an orthogonally orientedLED.

In another embodiment, a patient line state detector 1000 can alsodetermine whether a tubing segment 34 a is present in channel 1012. Inone aspect, a first LED 1028 and a second LED 1030 may be positionednext to one another. One LED (e.g., LED 1028) may be positioned so thatits optical axis passes through approximately the center of a properlypositioned translucent or transparent conduit or tubing segment 34 a inchannel 1012. The second LED (e.g. LED 1030) may be positioned so thatits optical axis is shifted slightly off center with respect to conduitor tubing segment 34 a in channel 1012. Such an on-center/off-centerpairing of LED's on one side of channel 1012, with an optical sensor1026 on the opposing side of channel 1012, has been shown to increasethe reliability of determining whether a liquid conduit or tubingsegment 34 a is present or absent within channel 1012. In a series oftests in which a tubing segment 34 a was alternately absent, present butimproperly positioned, or present and properly positioned within channel1012, signal measurements were taken by the optical sensor 1026 from thefirst LED and the second LED 1030. The signals received from each LEDwere plotted against each other, and the results are shown in FIG. 9-14.

As shown in FIG. 9-14, in the majority of cases in which tubing segment34 a was absent from channel 1012 (region 1039), the signal strengthreceived by optical sensor 1026 attributable to LEDa (LEDa receptionstrength) was found not to be significantly different from the signalstrength received from LEDa during a calibration step in which LEDa wasilluminated in a known absence of any tubing in channel 1012. Similarly,the signal strength associated with LEDb (LEDb reception strength), wasfound not to be significantly different from LEDb during a calibrationstep in which LEDb was illuminated in a known absence of any tubing inchannel 1012. Patient line state detector 1000 can reliably determinethat no tube is present within channel 1012 if the ratio of LEDa to itscalibration value, and the ratio of LEDb to its calibration value areeach approximately 1±20%. In a preferred embodiment, the threshold ratiocan be set at 1±15%. In an embodiment in which patient line statedetector 1000 is used in conjunction with a peritoneal dialysis cycler,LEDa and LEDb values within region 1039 of FIG. 9-14, for example, canbe used to indicate the absence of tube segment 34 a from channel 1012.The cycler controller can be programmed to pause further pumping actionsand inform the user via user interface 144 of the need to properlyposition the distal end of patient line 34 within patient line statedetector 1000.

The configuration and alignment of the three LED's and the opticalsensor 1026 described above is capable of generating the required datausing translucent or transparent fluid conduits (e.g. tubing segment 34a) having a wide range of translucence. In additional testing, patientline state detector 1000 was found to be capable of providing reliabledata to distinguish liquid from air in a fluid conduit, or the presenceor absence of a fluid conduit, using samples of tubing havingsignificantly different degrees of translucence. It was also capable ofproviding reliable data regardless of whether the PVC tubing being usedwas unsterilized, or sterilized (e.g., EtOx-sterilized).

The measurements taken by the optical sensor 1026 from the LED's can beused as inputs to a patient line state detector algorithm in order todetect the state of tubing segment 34 a. Besides detecting a full,empty, or absent tubing segment 34 a, the result of the algorithm may beindeterminate, possibly indicating movement or improper positioning ofthe tubing segment 34 a within the patient line state detector 1000, orpossibly the presence of a foreign object in channel 1012 of patientline state detector 1000. Manufacturing variations may cause the outputfrom the LED's and the sensitivity of optical sensor 1026 to vary amongdifferent assemblies. Therefore, it may be advantageous to perform aninitial calibration of the patient line state detector 1000. Forexample, the following procedure may be used to obtain calibrationvalues of the LED's and sensor:

-   -   (1) Ensure that no tubing segment 34 a is loaded in the patient        line state detector 1000.    -   (2) Poll the optical sensor 1026 in four different states:        -   (a) no LED illuminated        -   (b) first LED 1028 (LEDa) illuminated        -   (c) second LED 1030 (LEDb) illuminated        -   (d) third LED 1032 (LEDc) illuminated    -   (3) Subtract the ‘no LED illuminated’ signal value from each of        the other signal values to determine their ambient corrected        values, and store these three readings as ‘no-tube’ calibration        values.

Once calibration values for the LED's and sensor are obtained, the stateof tubing segment 34 a may then be detected. In this illustrativeembodiment, the patient line state detector algorithm performs a statedetection in a test as follows:

-   -   (1) Poll the optical sensor 1026 in four different states:        -   (a) no LED illuminated        -   (b) first LED 1028 (LEDa) illuminated        -   (c) second LED 1030 (LEDb) illuminated        -   (d) third LED 1032 (LEDc) illuminated    -   (2) Subtract the ‘no LED illuminated’ value from each of the        other values to determine their ambient corrected values.    -   (3) Calculate the relative LED values by dividing the test        values associated with each LED by their corresponding        calibration (‘no-tube’) values.

Results:

-   -   If the ambient corrected LEDa value is less than 0.10, then        there may be a foreign object in the detector, or an        indeterminate result can be reported to the user.    -   If the ambient corrected LEDa and LEDb values fall within ±15%        of their respective stored calibration (no-tube) values, then        report to the user that no tubing segment is present in the        detector.    -   If the ambient corrected LEDb value is equal to or greater than        about 40% of its stored calibration (‘no-tube’) value,        -   (a) check the signal associated with LEDc            -   (i) if the ambient corrected signal associated with LEDc                is equal or greater than about 150% of its calibration                (‘no-tube’) value, then report to the user that the                tubing segment is empty.            -   (ii) If the ambient corrected signal associated with                LEDc is equal to or less than about 125% of its                calibration (‘no-tube’) value, then report to the user                that the tubing segment is filled with liquid.            -   (iii) Otherwise, the result is indeterminate, and either                repeat the measurement (e.g., the tubing segment may be                moving, may be indented, or otherwise obscured), or                report to the user that the tubing segment should be                checked to ensure that it is properly inserted in the                detector.    -   If the ambient corrected LEDb value is less than about 40% of        its stored calibration (‘no-tube’) value, then the LEDc        threshold for determining the presence of a dry tube may be        greater. In an embodiment, for example, the LEDc empty tube        threshold was found empirically to follow the relationship:        [LEDc empty tube threshold]=−3.75×[LEDb value]+3.

Once it is determined that the tubing segment 34 a has been loaded inthe patient line state detector 1000, the patient line state detectoralgorithm can perform the following:

-   -   a) Poll the optical sensor 1026 with no LED illuminated and        store this as the no LED value.    -   b) Illuminate LEDc    -   c) Poll the optical sensor 1026, subtract the no LED value from        the LEDc value, and store this as the initial value.    -   d) Begin pumping    -   e) Poll the optical sensor 1026 and subtract the no LED value        from the subsequent LEDc value.    -   f) If this value is less than 75% of the initial value, then        conclude that tubing segment 34 a is filled with liquid, stop        pumping, confirm the detector state using the above procedure,        and when indicated, report to the user that priming is complete.        Otherwise, keep repeating the poll, calculation, and comparison.        In an embodiment, the system controller can be programmed to        perform the polling protocol as frequently as desired, such as,        for example, every 0.005 to 0.01 seconds. In an embodiment, the        entire polling cycle can conveniently be performed every 0.5        seconds.

FIG. 9-12A shows the results of sample calibration procedures for sixcyclers. The signal strength range that distinguishes a dry tube from awet tube (‘wet/dry threshold’ ranges) is noted to vary among thedifferent cyclers. (The variations in these ranges may be due to minorvariations in manufacturing, assembly and positioning of the variouscomponents). Thus at calibration, each cycler may be assigned a wet/drythreshold signal strength range that optimally separates the data pointsgenerated with a dry tube from the data points generated with a wettube.

FIG. 9-5 shows a perspective view of a second configuration of a patientline state detector 1000. Two or more different patient line statedetector configurations may necessary to accommodate varying types ofpatient connectors. In this illustrative embodiment, the secondconfiguration patient line state detector 1000 may include most of thesame components as in the first configuration patient line statedetector 1000. However, in order to accommodate a different type ofconnector, the second configuration may include a raised element 1036above housing 1006, rather than the stabilizing tab 1010 found in thefirst configuration patient line state detector 1000. The raised element1036 may generally conform to the shape of a standard patient lineconnector cap or connector flange.

In accordance with an aspect of the disclosure, detector housing 1006may not include a tube portion 1014. Therefore, open cavity 1008 may bearranged to allow placement of detector circuit board 1022 so that theLED's and optical sensor may be positioned next to a translucent ortransparent patient line connector 36 rather than a section of tubing.Channel 1012 consequently may be shaped differently to accommodate thetransmission of LED light through connector 36.

Solution Line Organizer

FIG. 9-6, FIG. 9-7, and FIG. 9-8, show a perspective view of the frontof an unloaded organizer 1038, a perspective view of the back of anunloaded organizer 1038, and a perspective view of a loaded organizer1038 respectively. In this embodiment, the organizer 1038 may besubstantially formed from a moderately flexible material (such as, e.g.,PAXON AL55-003 HDPE resin). Forming the organizer 1038 from this oranother relatively flexible polymer material increases the organizer's1038 durability when attaching and removing solution lines or solutionline connectors.

The organizer 1038 may conveniently be mounted or attached to an outerwall of the cycler housing 82. The organizer 1038 may include a tubeholder section 1040, a base 1042, and a tab 1044. The tube holdersection 1040, the base 1042, and the tab 1044 may all be flexiblyconnected, and may be substantially formed from the same HDPE-basedmaterial. The tube holder section 1040 may have a generally rectangularshape, and may include a generally flat top edge and a bottom edge thatmay be slightly curved in an outwardly direction. The tube holdersection 1040 may include a series of recessed segments 1046 that extendhorizontally along the bottom edge of the tube holder section 1040. Eachof the recessed segments 1046 may be separated by a series of supportcolumns 1048, which may also define the shape and size of the segments1046. The tube holder section 1040 may also include a raised area thatextends horizontally along the top edge of the tube holder section 1040.The raised area may include a plurality of slots 1050. The slots 1050may be defined in a vertical orientation, and may extend from the topedge of the tube holder section 1040 to the top of the recessed segments1046. The slots 1050 may have a generally cylindrical shape so as toconform to the shape of a drain line 28, solution line 30, or patientline 34. The depth of the slots 1050 may be such that the opening of theslot 1050 is narrower then the inner region of the slot 1050. Therefore,once a line is placed into the slot 1050 it becomes locked or snap-fitinto place. The line may then require a pre-determined minimum amount offorce to be removed from the slot 1050. This ensures that the lines arenot unintentionally removed from the organizer 1050.

In one aspect, the tab 1044 may be flexibly connected to the top edge ofthe tube holder section 1040. The tab 1044 may have a generallyrectangular shape. In another embodiment, the tab 1044 may also includetwo slightly larger radius corners. The tab 1044 may also include twovertically extending support columns 1048. The support columns 1048 maybe connected to the top edge of the tube holder section 1040, and mayextend in an upward direction into the tab 1044. In alternativeembodiment, the length and number of the support columns 1048 may varydepending on the desired degree of flexibility of the tab 1044. Inanother aspect, the tab 1044 may include a ribbed area 1052. The purposeof the tab 1044 and the ribbed area 1052 is to allow the organizer 1038to be easily grasped by a user so that the user can easily install,transport, or remove the solution lines 30 from the organizer 1038.Also, the tab 1044 provides an additional area of support when removingand loading the lines into the organizer 1038.

In another aspect, the base 1042 may be flexibly connected to the bottomedge of the tube holder section 1040. The base 1042 may have a generallyrectangular shape. In another embodiment, the base 1042 may also includetwo slightly larger radius corners. The base 1042 may include anelongated recessed segment 1046, which may be defined by a support ring1054 that surrounds the recessed segment 1046. The support columns 1050,the support ring 1054, and the raised area may all create a series ofvoids 1056 along the back of the organizer 1038 (shown, e.g., in FIG.9-7).

FIG. 9-9 and FIG. 9-10 show a perspective view of an organizer clip1058, and a perspective view of an organizer clip receiver 1060respectively. In these illustrative embodiments, the clip 1058 may bemade from a relatively high durometer polyurethane elastomer, such as,for example, 80 Shore A durometer urethane. In an alternativeembodiment, the clip 1058 may be made from any type of flexible anddurable material that would allow the organizer 1038 to flex and pivotalong the base 1042 when positioned in the clip 1058. The clip 1058 maybe “U-shaped”, and may include a back portion that extends slightlyhigher than a front portion. Additionally, there may be a lip 1062 thatextends along the top edge of the front portion of the clip 1058. Thelip 1062 extends slightly into the cavity of the clip 1058. The backportion of the clip 1058 may also include a plurality of elastomericpegs 1064 connected to (or formed from) and extending away from the backportion of the clip 1058. The pegs 1064 may include both a cylindricalsection 1066 and a cone 1068. The cylindrical section 1066 may connectto the back portion of the clip 1058, and the cone 1068 may be attachedto an open end of the cylindrical section 1066. The pegs 1064 allow theclip 1058 to be permanently connected to the organizer clip receiver1060, by engaging the pegs 1064 within a plurality of holes 1070 in theorganizer clip receiver 1060.

The organizer clip receiver 1060 may include a plurality of chamferedtabs 1072. The chamfered tabs 1072 may mate with corresponding slots onthe back portion of the clip 1058 when the pegs 1064 are engaged withthe organizer clip receiver 1060. Once the chamfered tabs 1072 engagethe slots, they can extend through the back portion of the clip 1058,and act as locking mechanisms to hold the organizer 1038 in place whenpositioned into the clip 1058. When the organizer 1038 is positionedwithin the clip 1058, the chamfers 1072 fit into the void 1056 on theback of the base 1042, which was created by the raised support ring1054. Referring again to FIG. 9-7, and in accordance with another aspectof the present disclosure, there may be a plurality of ramps 1074extending outwardly from the back of the organizer 1038. The ramps 1074may be generally shaped as inclined planes. This allows the organizer1038 to angle away from the cycler 14 when placed into the clip 1058,which provides numerous advantages over previous designs. For example,in this illustrative embodiment, the angle of the organizer 1038 ensuresthat neither the tab 1044, nor any of the lines (or line caps) connectedto the organizer 1038 are allowed to interfere with the heater lid 143when the lid 143 is being opened and closed. Additionally, the angle ofthe organizer 1038 in relation to the cycler 14, coupled with theflexibility of the organizer 1038, both encourage the user to remove thesolution lines 30 from the bottom instead of from the connector end 30 aof the solution lines. Preferably, the user should not remove thesolution lines 30 by grasping the connector ends 30 a, because in doingso the user could inadvertently remove one or more caps 31, which couldcause contamination and spills. Another advantage of the organizer 1038is that it aids the user in connecting color coded solution lines 30 tothe correct containers 20 by helping to separate the color coded lines30.

Door Latch Sensor

FIG. 9-11, shows a perspective view of a door latch sensor assembly1076. In this illustrative embodiment, the door latch sensor assembly1076 may include a magnet 1078 that is attached or connected to doorlatch 1080, and can pivot with door latch 1080 as it pivots into and ourof a latching position with its mating base unit catch 1082. A sensor(not shown in FIG. 9-11) may be positioned behind the front panel 1084of cycler 14, near base unit catch 1082, to detect the presence ofmagnet 1078 as door latch 1080 engages with base unit catch 1082. In oneembodiment, the sensor may be an analog Hall effect sensor. The purposeof the door latch sensor assembly 1076 is to confirm both that the door141 is closed and that the door latch 1080 is sufficiently engaged withcatch 1082 to ensure a structurally sound connection. FIG. 9-11 a showsa cross-sectional view of the door latch sensor assembly 1076. Sensor1079 is positioned on a circuit board 1077 behind front panel 1084.Sensor 1079 is preferably oriented off-axis from the line of motion ofmagnet 1078, because in this orientation, sensor 1079 is better able toresolve a variety of positions of magnet 1078 as it approaches frontpanel 1084 as door 141 is closed.

In one example, the door 141 may be considered to be sufficientlyengaged when the door latch 1080 has at least a 50% engagement with thecatch 1082. In one embodiment, the door latch 1080 may engage to adegree of approximately 0.120 inch nominally. Additionally, the sensor1079 may only sense a closed door 141 when the door latch 1080 issufficiently engaged with the catch 1082. Therefore, the sensor 1082 mayonly sense a closed door 141 when the door latch 1080 is engaged to adegree of approximately 0.060 inch. These engagement thresholds for thedoor latch 1080 may be set approximately at the middle range foracceptable engagement between the door latch 1080 and the catch 1082.This can help to ensure a robust design by accounting for sensor driftdue to time, temperature, and other variations. Testing was conducted todetermine the robustness of the sensor 1082 by collecting numerousmeasurements both at room temperature (approximately 24° C.) and at anabnormally cold temperature (approximately −2° C. to 9° C.). The roomtemperature readings were repeatedly higher than the cold readings, butonly by a small percentage of the 0 inch to 0.060 inch range. In oneaspect, the output of the sensor 1079 may be ratiometric to the voltagesupplied.

Therefore, both the supply voltage and the output of the sensor 1079 maybe measured (see formulas below, where the supply voltage and the outputof the sensor 1079 are represented by Door_Latch and Monitor_5V0respectively). Both the output of the sensor 1079 as well as the voltagesupplied may then pass through ¼ resistor dividers. Dividing the outputof the sensor 1079 and the voltage supplied may allow for a stableoutput to be produced. This procedure may ensure that the output remainsstable even if the supply voltage fluctuates.

In another aspect, the sensor 1079 may respond to both positive andnegative magnetic fields. Consequently, if there is no magnetic field,the sensor 1079 may output half the supply voltage. Additionally, apositive magnetic field may cause the output of the sensor 1079 toincrease, while a negative magnetic field may result in a decrease ofthe output of the sensor 1079. In order to obtain an accuratemeasurement of the output from the sensor 1079, the magnet polarity canbe ignored, and the supply voltage can simultaneously be compensatedfor. The following formula may be used to calculate the latch sensorratio:

Latch Sensor Ratio=absolutevalue((VDoor_Latch/VMonitor_5V0)−noFieldRatio)  (1)

Where the noFieldRatio is calculated by (VDoor_Latch/VMonitor_5 V0) withthe door 141 fully open.

Using this formula:

-   -   Ratio=0.0 indicates no magnetic field    -   Ratio >0.0 indicates some magnetic field; direction        indeterminate.

Shims of various thicknesses may be used between the inside of door 141and front panel 1084 to vary the degree of engagement between latch 1080and catch 1082, in order to calibrate the strength of the magnetic fielddetected by sensor 1079 with various positions of engagement of the doorlatch assembly 1076. In one embodiment, this data can be used to developfield strength ratios with and without a shim, or in other embodimentswith several shims of varying thicknesses. In one example, the doorlatch sensor assembly 1076 may complete the procedure for determining ifthe door latch 1080 is sufficiently engaged with the catch 1082 byperforming the following:

Calculate the nearRatio and the farRatio:

nearRatio=noShimRatio−(0.025/0.060)×(noShimRatio−withShimRatio)  (2)

farRatio=noShimRatio−(0.035/0.060)×(noShimRatio−withShimRatio)  (3)

In an embodiment, the door latch sensor assembly 1076 may save thenoFieldRatio, nearRatio, and farRatio to a calibration file. The doorlatch sensor assembly 1076 may then load the noFieldRatio, nearRatio,and farRatio from the calibration file, and the sensor assembly 1076 maythen use the nearRatio and farRatio as the hysteresis limits for thesensor 1079. The door latch sensor assembly 1076 may then begin with theinitial condition that the door 141 is open, and then repeatedlycalculate the Latch Sensor Ratio. If the Latch Sensor Ratio is greaterthan the nearRatio, the door latch sensor assembly 1076 will change thelatch state to closed, and if the Latch Sensor Ratio is less than thefarRatio, the door latch sensor assembly 1076 will change the latchstate to open. In an alternative embodiment for the door latch sensorassembly 1076, a middleRatio can be calculated from the calibration databy averaging the noShimRatio and the withShimRatio. In this case,measurements greater than the middleRatio indicate that the door latch1080 is engaged, and measurements less than the middleRatio indicatethat the door latch 1080 is not engaged.

Set Loading and Operation

FIG. 10 shows a perspective view of the APD system 10 of FIG. 1 with thedoor 141 of the cycler 14 lowered into an open position, exposing amounting location 145 for the cassette 24 and a carriage 146 for thesolution lines 30. (In this embodiment, the door 141 is mounted by ahinge at a lower part of the door 141 to the cycler housing 82.) Whenloading the set 12, the cassette 24 is placed in the mounting location145 with the membrane 15 and the pump chamber side of the cassette 24facing upwardly, allowing the portions of the membrane 15 associatedwith the pump chambers and the valve ports to interact with a controlsurface 148 of the cycler 14 when the door 141 is closed. The mountinglocation 145 may be shaped so as to match the shape of the base member18, thereby ensuring proper orientation of the cassette 24 in themounting location 145. In this illustrative embodiment, the cassette 24and mounting location 145 have a generally rectangular shape with asingle larger radius corner which requires the user to place thecassette 24 in a proper orientation into the mounting location 145 orthe door 141 will not close. It should be understood, however, thatother shapes or orientation features for the cassette 24 and/or themounting location 145 are possible.

In accordance with an aspect of the invention, when the cassette 24 isplaced in the mounting location 145, the patient, drain and heater baglines 34, 28 and 26 are routed through a channel 40 in the door 141 tothe left as shown in FIG. 10. The channel 40, which may include guides41 or other features, may hold the patient, drain and heater bag lines34, 28 and 26 so that an occluder 147 may selectively close/open thelines for flow. Upon closing of door 141, occluder 147 can compress oneor more of patient, drain and heater bag lines 34, 28 and 26 againstoccluder stop 29. Generally, the occluder 147 may allow flow through thelines 34, 28 and 26 when the cycler 14 is operating (and operatingproperly), yet occlude the lines when the cycler 14 is powered down(and/or not operating properly). (Occlusion of the lines may beperformed by pressing on the lines, or otherwise pinching the lines toclose off the flow path in the lines.) Preferably, the occluder 147 mayselectively occlude at least the patient and drain lines 34 and 28.

When the cassette 24 is mounted and the door 141 is closed, the pumpchamber side of the cassette 24 and the membrane 15 may be pressed intocontact with the control surface 148, e.g., by an air bladder, spring orother suitable arrangement in the door 141 behind the mounting location145 that squeezes the cassette 24 between the mounting location 145 andthe control surface 148. This containment of the cassette 24 may pressthe membranes 15 and 16 into contact with walls and other features ofthe base member 18, thereby isolating channels and other flow paths ofthe cassette 24 as desired. The control surface 148 may include aflexible gasket or membrane, e.g., a sheet of silicone rubber or othermaterial, that is associated with the membrane 15 and can selectivelymove portions of the membrane 15 to cause pumping action in the pumpchambers 181 and opening/closing of valve ports of the cassette 24. Thecontrol surface 148 may be associated with the various portions of themembrane 15, e.g., placed into intimate contact with each other, so thatportions of the membrane 15 move in response to movement ofcorresponding portions of the control surface 148. For example, themembrane 15 and control surface 148 may be positioned close together,and a suitable vacuum (or pressure that is lower relative to ambient)may be introduced through vacuum ports suitably located in the controlsurface 148, and maintained, between the membrane 15 and the controlsurface 148 so that the membrane 15 and the control surface 148 areessentially stuck together, at least in regions of the membrane 15 thatrequire movement to open/close valve ports and/or to cause pumpingaction. In another embodiment, the membrane 15 and control surface 148may be adhered together, or otherwise suitably associated.

In some embodiments, the surface of the control surface 148 or gasketfacing the corresponding cassette membrane overlying the pump chambersand/or valves is textured or roughened. The texturing creates aplurality of small passages horizontally or tangentially along thesurface of the gasket when the gasket is pulled against the surface ofthe corresponding cassette membrane. This may improve evacuation of airbetween the gasket surface and the cassette membrane surface in thetextured locations. It may also improve the accuracy of pump chambervolume determinations using pressure-volume relationships (such as, forexample, in the FMS procedures described elsewhere), by minimizingtrapped pockets of air between the gasket and the membrane. It may alsoimprove the detection of any liquid that may leak into the potentialspace between the gasket and the cassette membrane. In an embodiment,the texturing may be accomplished by masking the portions of the gasketmold that do not form the portions of the gasket corresponding to thepump membrane and valve membrane locations. A chemical engraving processsuch as the Mold-Tech® texturing and chemical engraving process may thenbe applied to the unmasked portions of the gasket mold. Texturing mayalso be accomplished by any of a number of other processes, such as, forexample, sand blasting, laser etching, or utilizing a mold manufacturingprocess using electrical discharge machining.

Before closing the door 141 with the cassette 24 loaded, one or moresolution lines 30 may be loaded into the carriage 146. The end of eachsolution line 30 may include a cap 31 and a region 33 for labeling orattaching an indicator or identifier. The indicator, for example, can bean identification tag that snaps onto the tubing at indicator region 33.In accordance with an aspect of the invention and as will be discussedin more detail below, the carriage 146 and other components of thecycler 14 may be operated to remove the cap(s) 31 from lines 30,recognize the indicator for each line 30 (which may provide anindication as to the type of solution associated with the line, anamount of solution, etc.) and fluidly engage the lines 30 with arespective spike 160 of the cassette 24. This process may be done in anautomated way, e.g., after the door 141 is closed and the caps 31 andspikes 160 are enclosed in a space protected from human touch,potentially reducing the risk of contamination of the lines 30 and/orthe spikes 160 when connecting the two together. For example, uponclosing of the door 141, the indicator regions 33 may be assessed (e.g.,visually by a suitable imaging device and software-based imagerecognition, by RFID techniques, etc.) to identify what solutions areassociated with which lines 30. The aspect of the invention regardingthe ability to detect features of a line 30 by way of an indicator atindicator region 33 may provide benefits such as allowing a user toposition lines 30 in any location of the carriage 146 without having anaffect on system operation. That is, since the cycler 14 canautomatically detect solution line features, there is no need to ensurethat specific lines are positioned in particular locations on thecarriage 146 for the system to function properly. Instead, the cycler 14may identify which lines 30 are where, and control the cassette 24 andother system features appropriately. For example, one line 30 andconnected container may be intended to receive used dialysate, e.g., forlater testing. Since the cycler 14 can identify the presence of thesample supply line 30, the cycler 14 can route used dialysate to theappropriate spike 160 and line 30. As discussed above, since the spikes160 of the cassette 24 all feed into a common channel, the input fromany particular spike 160 can be routed in the cassette 24 in any desiredway by controlling valves and other cassette features.

With lines 30 mounted, the carriage 146 may be moved to the left asshown in FIG. 10 (again, while the door 141 is closed), positioning thecaps 31 over a respective spike cap 63 on a spike 160 of the cassette 24and adjacent a cap stripper 149. The cap stripper 149 may extendoutwardly (toward the door 141 from within a recess in the cycler 14housing) to engage the caps 31. (For example, the cap stripper 149 mayinclude five fork-shaped elements that engage with a correspondinggroove in the caps 31, allowing the cap stripper 149 to resistleft/right movement of the cap 31 relative to the cap stripper 149.) Byengaging the caps 31 with the cap stripper 149, the caps 31 may alsogrip the corresponding spike cap 63. Thereafter, with the caps 31engaged with corresponding spike caps 63, the carriage 146 and capstripper 149 may move to the right, removing the spike caps 63 from thespikes 160 that are engaged with a corresponding cap 31. (One possibleadvantage of this arrangement is that spike caps 63 are not removed inlocations where no solution line 30 is loaded because engagement of thecap 31 from a solution line 30 is required to remove a spike cap 63.Thus, if a solution line will not be connected to a spike 160, the capon the spike 160 is left in place.) The cap stripper 149 may then stoprightward movement (e.g., by contacting a stop), while the carriage 146continues movement to the right. As a result, the carriage 146 may pullthe terminal ends of the lines 30 from the caps 31, which remainattached to the cap stripper 149. With the caps 31 removed from thelines 30 (and the spike caps 63 still attached to the caps 31), the capstripper 149 may again retract with the caps 31 into the recess in thecycler 14 housing, clearing a path for movement of the carriage 146 andthe uncapped ends of the lines 30 toward the spikes 160. The carriage146 then moves left again, attaching the terminal ends of the lines 30with a respective spike 160 of the cassette 24. This connection may bemade by the spikes 160 piercing an otherwise closed end of the lines 30(e.g., the spikes may pierce a closed septum or wall in the terminalend), permitting fluid flow from the respective containers 20 to thecassette 24. In an embodiment, the wall or septum may be constructed ofa flexible and/or self-sealing material such as, for example, PVC,polypropylene, or silicone rubber.

In accordance with an aspect of the invention, the heater bag 22 may beplaced in the heater bag receiving section (e.g., a tray) 142, which isexposed by lifting a lid 143. (In this embodiment, the cycler 14includes a user or operator interface 144 that is pivotally mounted tothe housing 82, as discussed below. To allow the heater bag 22 to beplaced into the tray 142, the interface 144 may be pivoted upwardly outof the tray 142.) As is known in the art, the heater tray 142 may heatthe dialysate in the heater bag 22 to a suitable temperature, e.g., atemperature appropriate for introduction into the patient. In accordancewith an aspect of the invention, the lid 143 may be closed afterplacement of the heater bag 22 in the tray 142, e.g., to help trap heatto speed the heating process, and/or help prevent touching or othercontact with a relatively warm portion of the heater tray 142, such asits heating surfaces. In one embodiment, the lid 143 may be locked in aclosed position to prevent touching of heated portions of the tray 142,e.g., in the circumstance that portions of the tray 142 are heated totemperatures that may cause burning of the skin. Opening of the lid 143may be prevented, e.g., by a lock, until temperatures under the lid 143are suitably low.

In accordance with another aspect of the invention, the cycler 14includes a user or operator interface 144 that is pivotally mounted tothe cycler 14 housing and may be folded down into the heater tray 142.With the interface 144 folded down, the lid 143 may be closed to concealthe interface 144 and/or prevent contact with the interface 144. Theinterface 144 may be arranged to display information, e.g., in graphicalform, to a user, and receive input from the user, e.g., by using a touchscreen and graphical user interface. The interface 144 may include otherinput devices, such as buttons, dials, knobs, pointing devices, etc.With the set 12 connected, and containers 20 appropriately placed, theuser may interact with the interface 144 and cause the cycler 14 tostart a treatment and/or perform other functions.

However, prior to initiating a dialysis treatment cycle, the cycler 14must at least prime the cassette 24, the patient line 34, heater bag 22,etc., unless the set 12 is provided in a pre-primed condition (e.g., atthe manufacturing facility or otherwise before being put into use withthe cycler 14). Priming may be performed in a variety of ways, such ascontrolling the cassette 24 (namely the pumps and valves) to draw liquidfrom one or more solution containers 20 via a line 30 and pump theliquid through the various pathways of the cassette 24 so as to removeair from the cassette 24. Dialysate may be pumped into the heater bag22, e.g., for heating prior to delivery to the patient. Once thecassette 24 and heater bag line 26 are primed, the cycler 14 may nextprime the patient line 34. In one embodiment, the patient line 34 may beprimed by connecting the line 34 (e.g., by the connector 36) to asuitable port or other connection point on the cycler 14 and causing thecassette 24 to pump liquid into the patient line 34. The port orconnection point on the cycler 14 may be arranged to detect the arrivalof liquid at the end of the patient line (e.g., optically, by conductivesensor, or other), thus detecting that the patient line is primed. Asdiscussed above, different types of sets 12 may have differently sizedpatient lines 34, e.g., adult or pediatric size. In accordance with anaspect of the invention, the cycler 14 may detect the type of cassette24 (or at least the type of patient line 34) and control the cycler 14and cassette 24 accordingly. For example, the cycler 14 may determine avolume of liquid delivered by a pump in the cassette needed to prime thepatient line 34, and based on the volume, determine the size of thepatient line 34. Other techniques may be used, such as recognizing abarcode or other indicator on the cassette 24, patient line 34 or othercomponent that indicates the patient line type.

FIG. 11 shows a perspective view of the inner side of the door 141disconnected from the housing 82 of the cycler 14. This view moreclearly shows how the lines 30 are received in corresponding grooves inthe door 141 and the carriage 146 such that the indicator region 33 iscaptured in a specific slot of the carriage 146. With the indicator atindicator region 33 positioned appropriately when the tubing is mountedto the carriage 146, a reader or other device can identify indicia ofthe indicator, e.g., representing a type of solution in the container 20connected to the line 30, an amount of solution, a date of manufacture,an identity of the manufacturer, and so on. The carriage 146 is mountedon a pair of guides 130 at top and bottom ends of the carriage 146 (onlythe lower guide 130 is shown in FIG. 11). Thus, the carriage 146 canmove left to right on the door 141 along the guides 130. When movingtoward the cassette mounting location 145 (to the right in FIG. 11), thecarriage 146 can move until it contacts stops 131.

FIG. 11-1 and FIG. 11-2 show a perspective view of a carriage 146, andan enlarged perspective view of a solution line 30 loaded into thecarriage 146. In these illustrative embodiments, the carriage 146 mayhave the ability to move on the door 141 along the guide 130. Thecarriage 146 may include five slots 1086, and therefore may have theability to support up to five solution lines 30. Each slot 1086 mayinclude three different sections; a solution line section 1088, an IDsection 1090, and a clip 1092. The solution line section 1088 may have agenerally cylindrical shaped cavity that allows the solution lines 30 toremain organized and untangled when loaded into the carriage 146. Theclip 1092 may be located at the opposite end of each of the slots 1086,relative to the solution line section 1088. The purpose of the clip 1092is to provide a secure housing for a membrane port 1094 located at theconnector end 30 a of the solution line 30, and to prevent the solutionline 30 from moving during treatment.

In one embodiment of the present disclosure, the clip 1092 may have asemicircular shape, and may include a middle region that extendsslightly deeper than the two surrounding edge regions. The purpose ofincluding the deeper middle region is to accommodate a membrane portflange 1096. The flange 1096 may have a substantially greater radiusthan the rest of the membrane port. Therefore, the deeper middle regionis designed to fit the wider flange 1096, while the two edge regionsprovide support so that the membrane port 1094 is immobilized.Additionally, the deep middle region may have two cutouts 1098positioned on opposite sides of the semicircle. The cutouts 1098 mayhave a generally rectangular shape so as to allow a small portion of theflange 1096 to extend into each of the cutouts 1098 when positioned inthe clip 1092. The cutouts 1098 may be formed so that the distancebetween the top edges of each cutout 1098 is slightly less than theradius of the flange 1096. Therefore, a sufficient amount of force isrequired to snap the flange 1096 into the clip 1092. Also, allowing forthe distance between the top edges of the two cutouts 1098 to be lessthan the radius of the flange 1096 helps to keep the solution line 30from inadvertently becoming dislodged during treatment.

In this illustrative embodiment, the carriage 146 may provide superiorperformance over previous designs because of its ability to counteractany deformation of the membrane ports 1094. The carriage 146 is designedto stretch the membrane ports 1094 between the front of the flange 1096and the back of the sleeve. If the membrane port 1094 is furtherstretched at any point during treatment, a wall in the carriage 146 maysupport the flange 1096.

In accordance with another aspect of the present disclosure, the IDsection 1090 may be positioned between the solution line section 1088and the clip 1092. The ID section 1090 may have a generally rectangularshape, thus having the ability to house an identification tag 1100 thatmay snap onto the solution line 30 at the indicator region 33. Theindicator region 33 may have an annular shape that is sized andconfigured to fit within the ID section 1090 when mounted in thecarriage 146. The identification tag 1100 may provide an indication asto the type of solution associated with each line 30, the amount ofsolution, a date of manufacture, and an identity of the manufacturer. Asshown in FIG. 11-1, the ID section 1090 may include a two dimensional(2-D) barcode 1102, which may be imprinted on the bottom of the IDsection 1090. The barcode 1102 may be a Data Matrix symbol with 10blocks per side, and may include an “empty” Data Matrix code. Thebarcode 1102 may be positioned on the carriage 146 underneath theidentification tag 1100, when the solution lines 30 are loaded into thecarriage 146. However, in an alternative embodiment, the barcode 1102may be added to the ID section 1090 of the carriage 146 by way of asticker or laser engraving. Also, in another embodiment, the barcode1102 may include a Data Matrix that consists of varying dimensions oflength and width, as well as varying numbers of blocks per side.

In this illustrative embodiment, however, the specific number of blockper side, and the specific length and width of each barcode 1102 wasspecifically chosen in order to provide the most robust design under avariety of conditions. Using only 10 blocks per side may result in thebarcode 1102 having larger blocks, which therefore ensures that thebarcode 1102 is easily readable, even under the dark conditions thatexist inside of the cycler housing 82.

FIG. 11-3 and FIG. 11-4 show a perspective view of a foldedidentification tag 1100, and a perspective view of a carriage driveassembly 132 including an AutoID camera 1104 mounted to an AutoID cameraboard 1106 respectively. In accordance with an aspect of the presentdisclosure, the identification tag 1100 may be formed from an injectionmold, and it may then fold to snap around the indicator region 33. Theidentification tag 1100 may include edges that are rounded, which mayprevent damage to the solution containers 20 during shipping. Theidentification tag 1100 may also include an 8×8 mm two dimensional (2-D)Data Matrix symbol 1103 with 18 blocks per side plus a quiet zone, whichmay be added by way of a sticker. The information contained in theseData Matrix symbols 1103 may be provided from the camera 1104 to thecontrol system 16, which may then obtain indicia, through variousprocesses such as by way of image analysis. Therefore, the AutoID camera1104 will have the ability to detect slots 1086 that contain a solutionline 30 that is correctly installed, a line 30 that is incorrectlyinstalled, or the absence of a line 30. A solution line 30 that iscorrectly installed will allow the camera 1104 to detect the Data Matrixsymbol 1103 located on the identification tag 1100, the absence of asolution line 30 will allow the camera 1104 to detect an “empty” DataMatrix barcode 1102 located on the carriage 146 underneath the membraneport 1094, and a solution line 30 that is incorrectly loaded willocclude the “empty” Data Matrix barcode 1102, resulting in no DataMatrix being decoded by the camera 1104 for that slot. Thus, the camera1104 should always decode a Data Matrix in every slot 1086 on thecarriage 146, baring an incorrectly loaded solution line 30.

In this illustrative embodiment, ability to detect features of asolution line 30 by way of an identification tag 1100 located atindicator region 33 may provide benefits such as allowing a user toposition lines 30 in any location of the carriage 146 without having aneffect on system operation. Additionally, since the cycler 14 canautomatically detect solution line features, there is no need to ensurethat specific lines 30 are positioned in particular locations on thecarriage 146 for the system to function properly. Instead, the cycler 14may identify which lines 30 are where, and control the cassette 24 andother system features appropriately.

In accordance with another aspect of the disclosure, the identificationtag 1100 must face into the carriage drive assembly 132 in order to bedecoded by the camera 1104. To ensure this, the carriage 146 andidentification tag 1100 may have complementary alignment features.

Additionally, the solution lines 30 with identification tags 1100 shouldalso fit within the Cleanflash machine, thus, the solution line 30 withidentification tag 1100 may be constructed to fit within a 0.53 inchdiameter cylinder. In an embodiment, the alignment feature may be asimple flat bottomed bill on the identification tag 1100 and matchingrib in the carriage 146. In one embodiment of the present disclosure,the bill and rib may slightly interfere, forcing the back of theidentification tag 1100 in an upward direction. While this configurationmay create a small amount of misalignment, it reduces misalignment inthe other axis. Finally, to ensure that the identification tag 1100 isproperly seated, the front of the carriage drive assembly 132 can bedesigned with only about 0.02 inch of clearance over the presentcarriage 146 and identification tag 1100 alignment.

In accordance with another aspect of the disclosure, the AutoID cameraboard 1106 may be mounted to the back of the carriage drive assembly132. Additionally, the AutoID camera 1104 may be mounted to the cameraboard 1106. The camera board 1106 may be placed approximately 4.19inches from the identification tag 1100. However, in an alternativeembodiment, the camera board 1106 may be moved backward without anyserious consequences. A plastic window 1108 may also be attached to thefront of the carriage drive assembly 132, which may allow theidentification tags 1100 to be imaged while also preventing fluid andfinger ingress. The AutoID camera 1104 may include a camera lens, whichmay be any type of lens, such as those used for security applications,or lenses intended for camera phones with the IR filter removed. Inaccordance with an aspect of the present disclosure, the camera lens mayconsist of a small size, light weight, low cost, and high image quality.

Additionally, a single SMD IR LED 1110 may be attached to the cameraboard 1106.

The LED 1110 may then illuminate the identification tags 1100 so thatthe camera 1104 may easily decode the Data Matrices. It is importantthat the identification tags 1100 be illuminated because the environmentinside of the cycler housing 82 is mostly absent of light. Therefore,without the LED 1110 to illuminate the identification tags 1100 thecamera 1104 would be unable to decode the Data Matrixes. Furthermore, toavoid creating glare in front of the identification tags 1100, the LED1110 may be mounted 0.75 inch away from the camera 1104. An FPGA mayalso be mounted to the camera board 1106, and may act as an intermediarybetween the OV3640 image sensor and Voyager's UI processor. In additionto making the processor's job easier, this architecture may allow for adifferent image sensor to be used without a change to any other Voyagerhardware or software. Finally, image decoding is handled by the opensource package libdmtx, which is addressable from a number ofprogramming languages and can run from a command line for testing.

FIG. 12 shows a perspective view of a carriage drive assembly 132 in afirst embodiment that functions to move the carriage 146 to remove thecaps from spikes 160 on the cassette, remove caps 31 on the solutionlines 30 and connect lines 30 to the spikes 160. A drive element 133 isarranged to move left to right along rods 134. In this illustrativeembodiment, an air bladder powers the movement of the drive element 133along the rods 134, but any suitable drive mechanism may be used,including motors, hydraulic systems, etc. The drive element 133 hasforwardly extending tabs 135 that engage with corresponding slots 146 aon the carriage 146 (see FIG. 11, which shows a top slot 146 a on thecarriage 146). Engagement of the tabs 135 with the slots 146 a allow thedrive element 133 to move the carriage 146 along the guides 130. Thedrive element 133 also includes a window 136, through which an imagingdevice, such as a CCD or CMOS imager, may capture image information ofthe indicators at indicator regions 33 on the lines 30 mounted to thecarriage 146. Image information regarding the indicators at indicatorregions 33 may be provided from the imaging device to the control system16, which may obtain indicia, e.g., by image analysis. The drive element133 can selectively move the cap stripper 149 both to the left and rightalong the rods 134. The cap stripper 149 extends forward and back usinga separate drive mechanism, such as a pneumatic bladder.

FIG. 13 shows a left side perspective view of the carriage driveassembly 132, which more clearly shows how a stripper element of the capstripper 149 is arranged to move in and out (a direction generallyperpendicular to the rods 134) along grooves 149 a in the housing of thecap stripper 149. Each of the semicircular cut outs of the stripperelement may engage a corresponding groove of a cap 31 on a line 30 byextending forwardly when the cap 31 is appropriately positioned in frontof the stripper 149 by the drive element 133 and the carriage 146. Withthe stripper element engaged with the caps 31, the cap stripper 149 maymove with the carriage 146 as the drive element 133 moves. FIG. 14 showsa partial rear view of the carriage drive assembly 132. In thisembodiment, the drive element 133 is moved toward the cassette 24mounting location 145 by a first air bladder 137 which expands to forcethe drive element 133 to move to the right in FIG. 14. The drive elementcan be moved to the left by a second air bladder 138. Alternatively,drive element 133 can be moved back and forth by means of one or moremotors coupled to a linear drive gear assembly, such as a ball screwassembly (in which the carriage drive assembly is attached to a ballnut), or a rack and pinion assembly, for example. The stripper element1491 of the cap stripper 149 can be moved in and out of the cap stripperhousing by a third bladder, or alternatively, by a motor coupled to alinear drive assembly, as described previously.

FIGS. 15-18 show another embodiment of a carriage drive assembly 132 andcap stripper 149. As can be seen in the rear view of the carriage driveassembly 132 in FIG. 15, in this embodiment the drive element 133 ismoved right and left by a screw drive mechanism 1321. As can be seen inthe right rear perspective view of the carriage drive assembly 132 inFIG. 16, the stripper element is moved outwardly and inwardly by an airbladder 139, although other arrangements are possible as describedabove.

FIGS. 17 and 18 show left and right front perspective views of anotherembodiment for the stripper element 1491 of the cap stripper 149. Thestripper element 1491 in the embodiment shown in FIG. 13 included onlyfork-shaped elements arranged to engage with a cap 31 of a solution line30. In the FIGS. 17 and 18 embodiment, the stripper element 1491 notonly includes the fork-shaped elements 60, but also rocker arms 61 thatare pivotally mounted to the stripper element 1491. As will be explainedin more detail below, the rocker arms 61 assist in removing spike caps63 from the cassette 24. Each of the rocker arms 61 includes a solutionline cap engagement portion 61 a and a spike cap engagement portion 61b. The rocker arms 61 are normally biased to move so that the spike capengagement portions 61 b are positioned near the stripper element 1491,as shown in the rocker arms 61 in FIG. 18. However, when a cap 31 isreceived by a corresponding fork-shaped element 60, the solution linecap engagement portion 61 a contacts the cap 31, which causes the rockerarm 61 to pivot so that the spike cap engagement portion 61 b moves awayfrom the stripper element 1491, as shown in FIG. 17. This positionenables the spike cap engagement portion 61 b to contact a spike cap 63,specifically a flange on the spike cap 63.

FIG. 19 shows a front view of the stripper element 1491 and the locationof several cross-sectional views shown in FIGS. 20-22. FIG. 20 shows therocker arm 61 with no spike cap 63 or solution line cap 31 positionednear the stripper element 1491. The rocker arm 61 is pivotally mountedto the stripper element 1491 at a point approximately midway between thespike cap engagement portion 61 b and the solution cap engagementportion 61 a. As mentioned above, the rocker arm 61 is normally biasedto rotate in a counterclockwise direction as shown in FIG. 20 so thatthe spike cap engagement portion 61 b is positioned near the stripperelement 1491. FIG. 21 shows that the rocker arm 61 maintains thisposition (i.e., with the spike cap engagement portion 61 b located nearthe stripper element 1491) even when the stripper element 1491 advancestoward a spike cap 63 in the absence of a solution line cap 31 engagingwith the fork-shaped element 60. As a result, the rocker arm 61 will notrotate clockwise or engage the spike cap 63 unless a solution line cap31 is present. Thus, a spike cap 63 that does not engage with a solutionline cap 31 will not be removed from the cassette 24.

FIG. 22 shows an example in which a solution line cap 31 is engaged withthe fork-shaped element 60 and contacts the solution line cap engagementportion 61 a of the rocker arm 61. This causes the rocker arm 61 torotate in a clockwise direction (as shown in the figure) and the spikecap engagement portion 61 b to engage with the spike cap 63. In thisembodiment, engagement of the portion 61 b includes positioning theportion 61 b adjacent a second flange 63 a on the spike cap 63 so thatwhen the stripper element 1491 moves to the right (as shown in FIG. 22),the spike cap engagement portion 61 b will contact the second flange 63a and help pull the spike cap 63 from the corresponding spike 160. Notethat the solution line cap 31 is made of a flexible material, such assilicone rubber, to allow a barb 63 c of the spike cap 63 to stretch thehole 31 b of cap 31 (see FIG. 23) and be captured by a circumferentialinner groove or recess within cap 31. A first flange 63 b on the spikecap 63 acts as a stop for the end of solution line cap 31. In anotherexample, the spike cap 63 does not include a first flange 63 b. Thewalls defining the groove or recess in the cap 31 hole 31 b may besymmetrical, or preferably asymmetrically arranged to conform to theshape of the barb 63 c. (See FIG. 33 for a cross sectional view of thecap 31 and the groove or recess.) The second flange 63 a on spike cap 63acts as a tooth with which the spike cap engagement portion 61 b of therocker arm 61 engages in order to provide an additional pulling force todisengage the spike cap 63 from the spike 160, if necessary.

FIG. 11-5 and FIG. 11-6 show two different perspective views of anotherembodiment for the stripper element 1491 of the cap stripper 149. Thestripper element 1491 in the embodiment shown in FIG. 13 usesfork-shaped elements 60 arranged to engage with a cap 31 of a solutionline 30. In the embodiment shown in FIG. 11-5, the stripper element 1491not only includes the fork-shaped elements 60, but may also include aplurality of sensing elements 1112, and a plurality of rocker arms 1114.The sensing elements 1112 and rocker arms 1114 may be arranged in twoparallel columns that run vertically along the stripper element 1491. Inan embodiment, each vertical column may contain five individual sensingelements 1112 and rocker arms 1114, each being positioned to generallyalign in a row corresponding with each of the fork-shaped elements 60.Each sensing element 1112 may be mechanically connected or linked to oneof the corresponding rocker arms 1114. In addition, the assemblycomprising each sensing element 1112 and rocker arm 1114 may include abiasing spring (not shown) that keeps each rocker arm 1114 biased towarda non-engagement position and sensing element 1112 in a position to becontacted and moved by the presence of a solution line cap 31 infork-shaped element 60. Each sensing element 1112 can be displaced andtilted toward the back of the stripper element 1491 by contact with acorresponding solution line cap 31 in forked-shaped element 60. Throughthe mechanical connection between sensing element 1112 and rocker arm1114, rocker arm 1114 can pivotally rotate or tilt laterally towardspike cap 63 upon contact between solution line cap 31 and sensingelement 1112. As rocker arm 1114 rotates or tilts toward spike cap 63,it can engage second flange 63 a on spike cap 63, allowing the stripperassembly to remove spike cap 63 from its corresponding spike.

FIGS. 11-7 a-c illustrate the relationship between sensing element 1112and a solution line cap 31, and between rocker arm 1114 and spike cap63. FIG. 11-7 c shows the sensing element 1112 and rocker arm 1114 inthe absence of a spike cap 63 and solution line cap 31. As shown in FIG.11-7 b, an outer flange 31 c of solution line cap 31 has a diametersufficiently large to make contact with sensing element 1112. As shownin FIG. 11-7 a, in the absence of a solution line cap 31, the merepresence of spike cap 63 alone does not contact sensing element 1112sufficiently enough to displace it and cause it to rotate away fromspike cap 63. As shown in FIG. 11-7 b, the displacement of sensingelement 1112 causes rotation or tilting of rocker arm 1114 toward spikecap 63, ultimately to the point of being positioned adjacent flange 63 aof spike cap 63. As shown in FIG. 11-7 a, when rocker arm 1114 is in anon-deployed position, it can clear the outer circumference of secondflange 63 a of spike cap 63 by a pre-determined amount (e.g., 0.040inch). Upon movement of rocker arm 1114 into a deployed position, itsrange of travel may be configured so as to provide a slight compressionforce against its corresponding spike cap 63 to ensure a secureengagement.

Once a rocker arm 1114 is positioned adjacent flange 63 a of a spike cap63, movement of stripper element 1491 to the right will engage spike cap63 via flange 63 a and help to pull spike cap 63 from its correspondingspike 160. In the absence of a solution line and its associated solutionline cap 31, stripper element 1491 will not remove the correspondingspike cap 63, keeping its associated spike 160 sealed. Thus, fewer thanthe maximum number of cassette spikes 161 may be accessed when fewerthan the maximum number of solution lines need to be used.

FIG. 23 shows a close-up exploded view of the connector end 30 a of asolution line 30 with the cap 31 removed. (In FIG. 23, the caps 31 areshown without a finger pull ring like that shown in FIG. 24 for clarity.A pull ring need not be present for operation of the cap 31 with thecycler 14. It may be useful, however, in allowing an operator tomanually remove the cap 31 from the terminal end of solution line 30, ifnecessary). In this illustrative embodiment, the indicator at indicatorregion 33 has an annular shape that is sized and configured to fitwithin a corresponding slot of the carriage 146 when mounted as shown inFIGS. 10 and 11. Of course, the indicator may take any suitable form.The cap 31 is arranged to fit over the extreme distal end of theconnector end 30 a, which has an internal bore, seals, and/or otherfeatures to enable a leak-free connection with a spike 160 on a cassette24. The connector end 30 a may include a pierceable wall or septum (notshown—see FIG. 33 item 30 b) that prevents leakage of solution in theline 30 from the connector end 30 a, even if the cap 31 is removed. Thewall or septum may be pierced by the spike 160 when the connector end 30a is attached to the cassette 24, allowing flow from the line 30 to thecassette 24. As discussed above, the cap 31 may include a groove 31 athat is engaged by a fork-shaped element 60 of the cap stripper 149. Thecap 31 may also include a hole 31 b that is arranged to receive a spikecap 63. The hole 31 b and the cap 31 may be arranged so that, with thecap stripper 149 engaged with the groove 31 a and the spike cap 63 of aspike 160 received in the hole 31 b, the cap 31 may grip the spike cap63 suitably so that when the carriage 146/cap stripper 149 pulls the cap31 away from the cassette 24, the spike cap 63 is removed from the spike160 and is carried by the cap 31. This removal may be assisted by therocker arm 61 engaging with the second flange 63 a or other feature onthe spike cap 63, as described above. Thereafter, the cap 31 and spikecap 63 may be removed from the connector end 30 a and the line 30attached to the spike 160 by the carriage 146.

Solution Line Connector Heater

In one embodiment, a connector heater may be provided near the indicatorregion 33 of the solution lines 30. The connector heater may control thetemperature of the connector end 30 a and in particular the pierceablewall or septum 30 b in order to limit the carriage force required attachthe solution lines to the spikes 160 on the cassette 24. There may beenough variation in ambient (room) temperature to affect the hardness ofthe pierceable wall or septum 30 b of the connector end 30 a of thesolution line, which may in turn affect the performance of the carriage146 in joining the spike 160 to the connector end 30 a of the solutionline 30. For example, at lower ambient temperatures, the increasedhardness of the pierceable wall or septum 30 b may require a greaterforce for spike 160 to penetrate it. On the other hand, at higherambient temperatures, the pierceable wall or septum may be so soft as todeform rather than separate when contacted by the spike 160.

The temperature of the connector ends 30 a may be controlled in a numberof ways, which may include placing a heating element in an appropriatelocation (e.g., at or near location 2807 on the door 141), installing atemperature sensor to monitor the temperature of connector ends 30 a,and using a controller to receive temperature data and modulate theoperation of the heating element. The temperature may be measured by atemperature sensor element mounted on the stripper element 1491 or onthe carriage 146. Alternatively, the temperature of the connector end 30a may be determined using an infra-red (IR) sensor tuned to measuresurface temperature of the connector end 30 a.

The controller may be a software process in the automation computer 300.Alternatively, the controller may be implemented in the hardwareinterface 310. The controller may modulate the power sent to aresistance heater, for example, in one of a number of ways. For example,the controller may send a PWM signal to a MOSFET that can modulate theflow of electrical power to the resistance heater. The controller maycontrol the measured temperature to the desired temperature through anumber of algorithms. One exemplary algorithm includes aproportional-integral (PI) feedback loop on the measured temperature toset the heater power. Alternatively, the heater power can be modulatedin an open loop algorithm that sets the heater power based on themeasured ambient temperature.

In another embodiment, the temperature of the connector end 30 a may becontrolled by mounting a radiant heater in the door 141 at location2807, for example, and aimed at the connector ends. Alternatively, thetemperature of the connector ends may be controlled by mounting athermo-electric element at location 2807, for example, on the door 141.The thermo-electric element may provide either heating or cooling to thearea surrounding the connector ends when mounted on the carriage 146.The radiant heater or thermo-electric element may be modulated by acontroller to maintain the temperature within a given range. Thepreferred temperature range for the connector end 30 a depends on thematerial comprising the pierceable wall or septum, and may be determinedempirically. In one embodiment, the piercable wall is PVC and thepreferred temperature range is set at about 10° C. to 30° C., or morepreferably to a temperature range of about 20° C. to 30° C.

In an embodiment, the connector heater near the indicator region 33 maybe used after the door is closed and before the solution lines 30 areattached to the cassette 24. The automation computer 300 or a controllerenables the connector heater if the measured temperature near theconnector 30 a is outside a preferred range. The automation computer 300or a controller may delay the auto-connection process until the measuredtemperature is within the preferred range. The connector heater may bedisabled after the auto-connection process is completed.

Once treatment is complete, or the line 30 and/or the cassette 24 areready for removal from cycler 14, the cap 31 and attached spike cap 63may be re-mounted on the spike 160 and the line 30 before the door 141is permitted to be opened and the cassette 24 and line 30 removed fromthe cycler 14. Alternatively, the cassette 24 and solution containerswith lines 30 can be removed en bloc from cycler 14 without re-mountingcap 31 and the attached spike cap 63. An advantage of this approachincludes a simplified removal process, and avoidance of any possiblefluid leaks onto the cycler or surrounding area from improperlyre-mounted or inadequately sealing caps.

FIGS. 24-32 show a perspective view of the carriage 146, cap stripper149 and cassette 24 during a line mounting and automatic connectionoperation. The door 141 and other cycler components are not shown forclarity. In FIG. 24, the carriage 146 is shown in a folded downposition, as if the door 141 is open in the position shown in FIG. 0.8.The lines 30 and cassette 24 are positioned to be lowered onto the door141. In FIG. 25, the lines 30 are loaded into the carriage 146 and thecassette 24 is loaded into the mounting location 145. At this point thedoor 141 can be closed to ready the cycler for operation. In FIG. 26,the door 141 is closed. Identifiers or indicators located at indicatorregion 33 on the lines 30 may be read to identify various linecharacteristics so that the cycler 14 can determine what solutions, howmuch solution, etc., are loaded. In FIG. 27, the carriage 146 has movedto the left, engaging the caps 31 on the lines 30 with correspondingspike caps 63 on the cassette 24. During the motion, the drive element133 engages the cap tripper 149 and moves the cap stripper 149 to theleft as well. However, the cap stripper 149 remains in a retractedposition. In FIG. 28, the cap stripper 149 moves forward to engage thefork-shaped elements 60 with the caps 31, thereby engaging the caps 31that have been coupled to the spike caps 63. If present, the rocker arms61 may move to an engagement position with respect to the spike caps 63.Next, as shown in FIG. 29, the carriage 146 and the cap stripper 149move to the right, away from the cassette 24 so as to pull the caps 31and spike caps 63 from the corresponding spikes 160 on the cassette 24.It is during this motion that the rocker arms 61, if present, may assistin pulling spike caps 63 from the cassette 24. In FIG. 30, the capstripper 149 has stopped its movement to the right, while the carriage146 continues to move away from the cassette 24. This causes theconnector ends 30 a of the lines 30 to be pulled from the caps 31,leaving the caps 31 and spike caps 63 mounted on the cap stripper 149 byway of the fork-shaped elements 60. In FIG. 31, the cap stripper 149retracts, clearing a path for the carriage 146 to move again toward thecassette 24. In FIG. 32, the carriage 146 moves toward the cassette 24to engage the connector ends 30 a of the lines 30 with the correspondingspikes 160 of the cassette 24. The carriage 146 may remain in thisposition during cycler operation. Once treatment is complete, themovements shown in FIGS. 24-32 may be reversed to recap the spikes 160and the solution lines 30 and remove the cassette 24 and/or lines 30from the cycler 14.

To further illustrate the removal of caps 31 and spike caps 63, FIG. 33shows a cross-sectional view of the cassette 24 at five different stagesof line 30 connection. At the top spike 160, the spike cap 63 is stillin place on the spike 160 and the solution line 30 is positioned awayfrom the cassette 24, as in FIG. 26. At the second spike 160 down fromthe top, the solution line 30 and cap 31 are engaged over the spike cap63, as in FIGS. 27 and 28. At this point, the cap stripper 149 mayengage the cap 31 and spike cap 63. At the third spike 160 from the top,the solution line 30, cap 31 and spike cap 63 have moved away from thecassette 24, as in FIG. 29. At this point, the cap stripper 149 may stopmovement to the right. At the fourth spike 160 from the top, thesolution line 30 continues movement to the right, removing the cap 31from the line 30, as in FIG. 30. Once the caps 31 and 63 are retracted,the solution line 30 moves to the left to fluidly connect the connectorend 30 a of the line 30 to the spike 160, as in FIG. 32. Various sensorscan be used to help verify that the carriage 146 and cap stripper 149move fully to their expected positions. In an embodiment, the carriagedrive assembly 132 can be equipped with six Hall effect sensors (notshown): four for the carriage 146 and two for the cap stripper 149. Afirst cap stripper sensor may be located to detect when the cap stripper149 is fully retracted. A second cap stripper sensor may be located todetect when the cap stripper 149 is fully extended. A first carriagesensor may be located to detect when the carriage 146 is in the “home”position, i.e. in position to permit loading the cassette 24 and lines30. A second carriage sensor may be located to detect when the carriage146 is in position to have engaged the spike caps 63. A third carriagesensor may be located to detect when the carriage 146 has reached aposition to have removed the caps 31 from the lines 30. A fourthcarriage sensor may be located to detect when the carriage 146 has movedto a position to have engaged the connector ends 30 a of the lines 30with the corresponding spikes 160 of the cassette 24. In otherembodiments, a single sensor can be used to detect more than one of thecarriage positions described above. The cap stripper and carriagesensors can provide input signals to an electronic control board(“autoconnect board”), which in turn can communicate specificconfirmation or error codes to the user via the user interface 144.

FIG. 11-6 shows a perspective view of an alternative embodiment of thecarriage drive assembly 132. The carriage drive assembly 132 in theembodiment shown in FIG. 12 included only the drive element 133, therods 134, the tabs 136, and the window 136. In the FIG. 11-6 embodiment,the carriage drive assembly 132 not only includes the drive element 133,the rods 134, the tabs 136, and the window 136, but may also include avertical column of AutoID view boxes 1116. The view boxes 1116 may bepositioned directly adjacent to the window 136. Also, the view boxes1116 may be positioned and shaped so that the horizontal axis of each ofthe five slots 1086 located on the carriage 146 run through the centerof a corresponding view box 1116, when the carriage 146 moves eitherright or left along the guides 130. The view boxes 1116 may allow forthe AutoID camera 1104, which is attached to the camera board 1106, todetect if the solution line caps 31 are positioned on the lines 30 priorto the engaging of the solution lines with the spike cap 63. This mayallow for confirmation that the user hasn't removed the caps 31prematurely. Once the presence or absence of the caps 31 is determined,the camera 1104 can provide a corresponding input signal to anelectronic control board (referred to as the autoconnect board later inthe specification), which in turn can communicate specific confirmationor error codes, relating to the presence of the caps 31 on the lines 30,to the user via the user interface 144.

In accordance with another aspect of the disclosure, the carriage driveassembly 132 may include an autoconnect board 1118. The autoconnectboard 1118 may be attached to the top of the carriage drive assembly132, and may extend the entire length of the assembly 132. In thisillustrative embodiment, there may also be an LED 1120 mounted to theautoconnect board 1118. The LED 1120 may be located in a fixed positiondirectly above the fork-shaped elements 60. Also, the LED 1120 may bedirected is a fashion so that the light being emitted from the LED 1120travels downward across the stripper element 1491. In accordance withanother aspect of the present disclosure, the carriage drive assembly132 may also include a fluid board 1122. The fluid board 1122 may beattached to the bottom of the carriage drive assembly 132, and may alsoextent the length of the assembly 132. In this illustrative embodiment,there may be a receiver 1124 (not pictured) mounted to the fluid board1122 at a location directly below the LED 1120, which is mounted to theautoconnect board 1118. Therefore, the LED 1120 can emit light acrossthe fork-shaped elements 60, and if the light it detected by thereceiver 1124 then there are no solution line caps 31 left in thestripper element 1491, however, if the light is interrupted on its waytowards the receiver 1124 then there may be a cap 31 left in thestripper element 1491. This LED 1120 and receiver 1124 combinationallows for the detection of caps 31 that may have been inadvertentlyleft in the stripper element 1491 either by the user or by the cycler14. In accordance with an aspect of the disclosure, the fluid board 1122may also have the ability to detect humidity, moisture, or any otherliquid that may be present inside of the carriage drive assembly 132,which could potentially cause the cycler 14 to fail.

There may be an advantage in adjusting the force with which the carriage146 engages the spike caps 63, depending on how many lines 30 are beinginstalled. The force required to complete a connection to the cassette24 increases with the number of caps 31 that must be coupled to spikecaps 63. The sensing device for detecting and reading information fromthe line indicators at indicator regions 33 can also be used to providethe data required to adjust the force applied to drive element 133. Theforce can be generated by a number of devices, including, for example,the first air bladder 137, or a linear actuator such as a motor/ballscrew. An electronic control board (such as, for example, theautoconnect board) can be programmed to receive input from the linedetection sensor(s), and send an appropriate control signal either tothe motor of a linear actuator, or to the pneumatic valve that controlsinflation of air bladder 137. The controller 16 can control the degreeor rate of movement of drive element 133, for example by modulating thevoltage applied to the motor of a linear actuator, or by modulating thepneumatic valve controlling the inflation of bladder 137.

In accordance with an aspect of the present disclosure, it may benecessary for the carriage drive assembly 132 to be capable ofgenerating a force of at least 550 N (124 lbf) on carriage 146, in orderto engage the membrane ports with spikes 160. This force is to bemeasured in the carriage direction of the membrane port spiking onto thecassette 24. The maximum force required to spike a sterilized PVCmembrane port onto the spike 160 may be 110 N. Additionally, the maximumforce required to spike a sterilized JPOC membrane port onto the spike160 may be 110 N. These force requirements ensure carriage driveassembly 132 is able to spike five JPOC ports. In an alternativeembodiment, the PVC port force requirement may be lowered further basedon current insertion forces.

The aspect of the invention by which caps 31 on lines 30 are removedtogether with caps 63 on spikes 160 of the cassette 24 may provide otheradvantages aside from simplicity of operation. For example, since spikecaps 63 are removed by way of their engagement with a cap 31 on a line30, if there is no line 30 mounted at a particular slot on the carriage146, the spike cap 63 at that position will not be removed. For example,although the cassette 24 includes five spikes 160 and correspondingspike caps 63, the cycler 14 can operate with four or less (even no)lines 30 associated with the cycler 14. For those slots on the carriage146 where no line 30 is present, there will be no cap 31, and thus nomechanism by which a spike cap 63 at that position can be removed. Thus,if no line 30 will be connected to a particular spike 160, the cap 63 onthat spike 160 may remain in place during use of the cassette 24. Thismay help prevent leakage at the spike 160 and/or contamination at thespike 160.

The cassette 24 in FIG. 33 includes a few features that are differentfrom those shown, for example, in the embodiment shown in FIGS. 3, 4 and6. In the FIGS. 3, 4 and 6 embodiment, the heater bag port 150, drainline port 152 and patient line port 154 are arranged to have a centraltube 156 and a skirt 158. However, as mentioned above and shown in FIG.33, the ports 150, 152, 154 may include only the central tube 156 and noskirt 158. This is also shown in FIG. 34. The embodiment depicted inFIG. 34 includes raised ribs formed on the outside surface of theleft-side pump chamber 181. The raised ribs may also be provided on theright-side pump chamber 181, and may provide additional contact pointsof the outside walls of pump chambers 181 with the mechanism in the door141 at the cassette mounting location 145, which presses the cassetteagainst the control surface 148 when the door 141 is closed. The raisedribs are not required, and instead the pump chambers 181 may have no ribor other features, as shown for the right-side pump chamber 181 in FIG.34. Similarly, the spikes 160 in the FIGS. 3, 4 and 6 embodiment includeno skirt or similar feature at the base of the spike 160, whereas theembodiment in FIG. 33 includes a skirt 160 a. This is also shown in FIG.34. The skirt 160 a may be arranged to receive the end of the spike cap63 in a recess between the skirt 160 a and the spike 160, helping toform a seal between the spike 160 and the spike cap 63.

Another inventive feature shown in FIG. 33 relates to the arrangement ofthe distal tip of the spike 163 and the lumen 159 through the spike 160.In this aspect, the distal tip of the spike 160 is positioned at or nearthe longitudinal axis of the spike 160, which runs generally along thegeometric center of the spike 160. Positioning the distal tip of thespike 160 at or near the longitudinal axis may help ease alignmenttolerances when engaging the spike 160 with a corresponding solutionline 30 and help the spike 160 puncture a septum or membrane 30 b in theconnector end 30 a of the line 30. As a result, the lumen 159 of thespike 160 is located generally off of the longitudinal axis of the spike160, e.g., near a bottom of the spike 160 as shown in FIG. 33 and asshown in an end view of a spike 160 in FIG. 35. Also, the distal end ofthe spike 160 has a somewhat reduced diameter as compared to moreproximal portions of the spike 160 (in this embodiment, the spike 160actually has a step change in diameter at about ⅔ of the length of thespike 160 from the body 18). The reduced diameter of the spike 160 atthe distal end may provide clearance between the spike 160 and the innerwall of the line 30, thus allowing the septum 30 b a space to fold backto be positioned between the spike 160 and the line 30 when pierced bythe spike 160. The stepped feature 160 b on the spike 160 (shown, e.g.,in FIG. 35A) may also be arranged to engage the line 30 at the locationwhere the septum 30 b is connected to the inner wall of the line 30,thus enhancing a seal formed between the line 30 and the spike 160. Inanother embodiment, as shown in FIG. 35A, the length of the base 160 cof spike 160 may be shortened to reduce the force required to remove thespike cap 63 from spike 160, or to reduce the force required to spikethe connector end 30 a of solution line 30. Shortening the base 160 creduces the area of frictional contact between spike 160 and its cap 63,or between spike 160 and the internal surface of connector end 30 a. Inaddition, the skirt 160 a at the base of spike 160 may be replaced byindividual posts 160 d. The posts 160 d allow the spike cap 63 to beproperly seated onto spike 160 while also allowing for more thoroughcirculation of sterilization fluid or gas around spike 160 during thesterilization process prior to or after packaging of the dialysatedelivery set 12.

To more fully take advantage of the embodiment shown in FIG. 35A, aspike cap 64, as shown in FIG. 35B may be used. A skirt 65 on the baseof spike cap 64 is constructed to fit snugly over the posts 160 d of thebase of spike 160 shown in FIG. 35A. In addition, interrupted ribs 66,67 within the inner circumference of the base of spike 160 may provide asnug fit between spike cap 64 and the base 160 c of spike 160, whilealso permitting sterilizing gas or fluid to penetrate more distally overthe base of a capped spike 160. As shown in FIG. 35C, in across-sectional view of spike cap 64, a set of three inner ribs 66, 67,68 may be used to provide a snug fit between spike cap 64 and the base160 c of spike 160. In an embodiment, rib 66 and rib 67 haveinterruptions or gaps 66 a and 67 a along their circumference to permitgas or fluid external to the cassette to flow over the base 160 c ofspike 160. A third rib 68 may be circumferentially intact in order tomake a sealing engagement between spike cap 64 and the base 160 c ofspike 160, sealing off the base 160 c from rest of the external surfaceof spike 160. In other embodiments, ribs within spike cap 64 may beoriented longitudinally rather than circumferentially, or in any otherorientation to provide a snug fit between spike cap 64 and spike 160,while also permitting an external gas or fluid to make contact with theoutside of the base 160 c of spike 160. In the embodiment shown, forexample, the outer surface of the cassette, spike cap and most of thebase 160 c of spike 160 can be sterilized by exposing the cassetteexternally to ethylene oxide gas. Because the diameter of the steppedfeature 160 b and the distal end of spike 160 are smaller than the innerdiameter of the overlying portion of spike cap 64, any gas or fluidentering the spike lumen from within the cassette can reach the outersurface of spike 160 up to the sealing rib 68. Thus any sterilizing gassuch as ethylene oxide entering the fluid passages of the cassette mayreach the remainder of the external surface of spike 160. In anembodiment, the gas may enter the cassette through a vented cap, forexample, on the end of patient line 34 or drain line 28.

The spike cap 34 may include 3 or more centering ribs 64D that contactthe end of the spike 160. The ribs 64D are oriented along the majoraccess of spike cap 34 and located near the closed end of the spike cap34. Preferably there are at least three ribs 63D to center the closedend of the cap on the spike without over constraining the cap/spikeorientation. The spike cap 64 includes a tapered end with a blunt tip tofacilitate the penetration of the spike cap 34 into the hole 31 b of thesolution cap 31. The tapered end will guide the spike cap 34 if itmisaligned with the hole 31 b. The blunt tip avoids snagging thesolution cap 31 unlike a sharp tip that might catch the inside edge ofthe hole 31 b and dig into the solution cap material. In contrast ablunt tip can slide past the edges of the hole 31 b.

Once the cassette 24 and lines 30 are loaded into the cycler 14, thecycler 14 must control the operation of the cassette 24 to move fluidfrom the solution lines 30 to the heater bag 22 and to the patient. FIG.36 shows a plan view of the control surface 148 of the cycler 14 thatinteracts with the pump chamber side of the cassette 24 (e.g., shown inFIG. 6) to cause fluid pumping and flowpath control in the cassette 24.When at rest, the control surface 148, which may be described as a typeof gasket, and comprise a sheet of silicone rubber, may be generallyflat. Valve control regions 1481 may (or may not) be defined in thecontrol surface 148, e.g., by a scoring, groove, rib or other feature inor on the sheet surface, and be arranged to be movable in a directiongenerally transverse to the plane of the sheet. By movinginwardly/outwardly, the valve control regions 1481 can move associatedportions of the membrane 15 on the cassette 24 so as to open and closerespective valve ports 184, 186, 190 and 192 of the cassette 24, andthus control flow in the cassette 24. Two larger regions, pump controlregions 1482, may likewise be movable so as to move associated shapedportions 151 of the membrane 15 that cooperate with the pump chambers181. Like the shaped portions 151 of the membrane 15, the pump controlregions 1482 may be shaped in a way to correspond to the shape of thepump chambers 181 when the control regions 1482 are extended into thepump chambers 181. In this way, the portion of the control sheet 148 atthe pump control regions 1482 need not necessarily be stretched orotherwise resiliently deformed during pumping operation.

Each of the regions 1481 and 1482 may have an associated vacuum orevacuation port 1483 that may be used to remove all or substantially allof any air or other fluid that may be present between the membrane 15 ofcassette 24, and the control surface 148 of cycler 14, e.g., after thecassette 24 is loaded into the cycler 14 and the door 141 closed. Thismay help ensure close contact of the membrane 15 with the controlregions 1481 and 1482, and help control the delivery of desired volumeswith pump operation and/or the open/closed state of the various valveports. Note that the vacuum ports 1482 are formed in locations where thecontrol surface 148 will not be pressed into contact with a wall orother relatively rigid feature of the cassette 24. For example, inaccordance with one aspect of the invention, one or both of the pumpchambers of the cassette may include a vacuum vent clearance regionformed adjacent the pump chamber. In this illustrative embodiment asshown in FIGS. 3 and 6, the base member 18 may include vacuum vent portclearance or extension features 182 (e.g., recessed areas that arefluidly connected to the pump chambers) adjacent and outside theoval-shaped depressions forming the pump chambers 181 to allow thevacuum vent port 1483 for the pump control region 1482 to remove any airor fluid from between membrane 15 and control surface 148 (e.g., due torupture of the membrane 15) without obstruction. The extension featuremay also be located within the perimeter of pump chamber 181. However,locating vent port feature 182 outside the perimeter of pump chamber 181may preserve more of the pumping chamber volume for pumping liquids,e.g., allows for the full footprint of pump chamber 181 to be used forpumping dialysate. Preferably, extension feature 182 is located in avertically lower position in relation to pump chamber 181, so that anyliquid that leaks between membrane 15 and control surface 148 is drawnout through vacuum port 1483 at the earliest opportunity. Similarly,vacuum ports 1483 associated with valves 1481 are preferably located ina vertically inferior position with respect to valves 1481.

FIG. 36A shows that control surface 148 may be constructed or molded tohave a rounded transition between the base element 1480 of controlsurface 148 and its valve and pump control regions 1481, 1482. Thejunctions 1491 and 1492 may be molded with a small radius to transitionfrom base element 1480 to valve control region 1481 and pump controlregion 1482, respectively. A rounded or smooth transition helps toprevent premature fatigue and fracture of the material comprisingcontrol surface 148, and may improve its longevity. In this embodiment,channels 1484 leading from vacuum ports 1483 to the pump control regions1482 and valve control regions 1481 may need to be lengthened somewhatto accommodate the transition feature.

The control regions 1481 and 1482 may be moved by controlling apneumatic pressure and/or volume on a side of the control surface 148opposite the cassette 24, e.g., on a back side of the rubber sheet thatforms the control surface 148. For example, as shown in FIG. 37, thecontrol surface 148 may be backed by a mating or pressure delivery block170 that includes control chambers or depressions 171A located inassociation with each control region 1481, and control chambers ordepressions 171B, located in association with each control region 1482,and that are isolated from each other (or at least can be controlledindependently of each other if desired). The surface of mating orpressure delivery block 170 forms a mating interface with cassette 24when cassette 24 is pressed into operative association with controlsurface 148 backed by mating block 170. The control chambers ordepressions of mating block 170 are thus coupled to complementary valveor pumping chambers of cassette 24, sandwiching control regions 1481 and1482 of control surface 148 adjacent to mating block 170, and theassociated regions of membrane 15 (such as shaped portion 151) adjacentto cassette 24. Air or other control fluid may be moved into or out ofthe control chambers or depressions 171A, 171B of mating block 170 forthe regions 1481, 1482, thereby moving the control regions 1481, 1482 asdesired to open/close valve ports of the cassette 24 and/or effectpumping action at the pump chambers 181. In one illustrative embodimentshown in FIG. 37, the control chambers 171A may be arranged ascylindrically-shaped regions backing each of the valve control regions1481. The control chambers or depressions 171B may comprise ellipsoid,ovoid or hemi-spheroid voids or depressions backing the pump controlregions 1482. Fluid control ports 173A may be provided for each controlchamber 171A so that the cycler 14 can control the volume of fluidand/or the pressure of fluid in each of the valve control chambers 1481.Fluid control ports 173C may be provided for each control chamber 171Bso that the cycler 14 can control the volume of fluid and/or thepressure of fluid in each of the volume control chambers 1482. Forexample, the mating block 170 may be mated with a manifold 172 thatincludes various ports, channels, openings, voids and/or other featuresthat communicate with the control chambers 171 and allow suitablepneumatic pressure/vacuum to be applied to the control chambers 171.Although not shown, control of the pneumatic pressure/vacuum may beperformed in any suitable way, such as through the use of controllablevalves, pumps, pressure sensors, accumulators, and so on. Of course, itshould be understood that the control regions 1481, 1482 may be moved inother ways, such as by gravity-based systems, hydraulic systems, and/ormechanical systems (such as by linear motors, etc.), or by a combinationof systems including pneumatic, hydraulic, gravity-based and mechanicalsystems.

FIG. 37A shows an exploded view of an integrated pressure distributionmodule or assembly 2700 for use in a fluid flow control apparatus foroperating a pumping cassette, and suitable for use as pressuredistribution manifold 172 and mating block 170 of cycler 14. FIG. 37Bshows a view of an integrated module 2700 comprising a pneumaticmanifold or block, ports for supply pressures, pneumatic control valves,pressure sensors, a pressure delivery or mating block and a controlsurface or actuator that includes regions comprising flexible membranesfor actuating pumps and valves on a pumping cassette. The integratedmodule 2700 may also include reference chambers within the pneumaticmanifold for an FMS volume measurement process for determining thevolume of fluid present in a pumping chamber of a pumping cassette. Theintegrated module may also comprise a vacuum port, and a set of pathwaysor channels from interfaces between the actuator and flexible pump andvalve membranes of a pumping cassette to a fluid trap and liquiddetection system. In some embodiments, the pneumatic manifold may beformed as a single block. In other embodiments, the pneumatic manifoldmay be formed from two or more manifold blocks mated together withgaskets positioned between the manifold blocks. The integrated module2700 occupies a relatively small space in a fluid flow controlapparatus, and eliminates the use of tubes or flexible conduitsconnecting the manifold ports with corresponding ports of a pressuredelivery module or block mated to a pumping cassette. Among otherpossible advantages, the integrated module 2700 reduces the size andassembly cost of the pneumatic actuation assembly of a peritonealdialysis cycler, which may result in a smaller and less expensivecycler. Additionally, the short distances between pressure or vacuumdistribution ports on the pressure distribution manifold block andcorresponding pressure or vacuum delivery ports on a mating pressuredelivery block, together with the rigidity of the conduits connectingthe ports, may improve the responsiveness of an attached pumpingcassette and the accuracy of cassette pump volume measurement processes.When used in a peritoneal dialysis cycler 14, in an embodiment, anintegrated module comprising a metallic pressure distribution manifoldmated directly to a metallic pressure delivery block may also reduce anytemperature differences between the control volume 171B and thereference chamber 174 of the cycler 14, which may improve the accuracyof the pump volume measurement process.

An exploded view of the integrated module 2700 is presented in FIG. 37A.The actuator surface, mounted on a mating block or pressure deliveryblock, is analogous or equivalent to the gasket or control surface 148,that includes flexible regions arranged to move back and forth to pumpfluid and/or open and close valves by pushing or pulling on a membrane15 of a pump cassette 24. With respect to cycler 14, the control surface148 is actuated by the positive and negative pneumatic pressure suppliedto the control volumes 171A, 171B behind the control regions 1481, 1482.The control surface 148 attaches to the pressure delivery block ormating block 170 by fitting tightly on a raised surface 2744 on thefront surface of the mating block 170 with a lip 2742. The mating block170 may include one or more surface depressions 2746 to align with andsupport the oval curved shape of one or more corresponding pump controlsurfaces 1482, forming a pump control chamber. A similar arrangement,with or without a surface depression, may be included in forming a valvecontrol region 171A to align with a corresponding control surface 1481for controlling one or more valves of a pumping cassette. The matingblock 170 may further include grooves 2748 on the surface of depression2746 of mating block 170 behind the pump control surface 1482 tofacilitate the flow of control fluid or gas from the port 173C to theentire back surface the pump control surface 1482. Alternatively, ratherthan having grooves 2748, the depression 2746 may be formed with aroughened surface or a tangentially porous surface.

The mating block 170 connects the pressure distribution manifold 172 tothe control surface 148, and delivers pressure or vacuum to variouscontrol regions on control surface 148. The mating block 170 may also bereferred to as a pressure delivery block in that it provides pneumaticconduits to supply pressure and vacuum to the valve control regions 1481and the pump control regions 1482, vacuum to the vacuum ports 1483 andconnections from the pump control volumes 171B to the pressure sensors.The ports 173A connect the valve control volumes 171A to the pressuredistribution manifold 172. The ports 173C connect the pump controlvolume 171B to the pressure distribution manifold 172. The vacuum ports1483 are connected to the pressure distribution manifold 172 via ports173B. In one embodiment, the ports 173B extend above the surface of thepressure delivery block 170 to pass through the control surface 148 toprovide vacuum at port 1483 without pulling the control surface 148 ontothe port 173B and blocking flow.

The pressure delivery block 170 is attached to the front face of thepressure distribution manifold 172. The ports 173A, 173B, 173C line upwith pneumatic circuits on the pressure distribution manifold 172 thatconnect to valve ports 2714. In one example, the pressure delivery block170 is mated to the pressure distribution manifold 172 with a front flatgasket 2703 clamped between them. The block 170 and manifold 172 areheld together mechanically, which in an embodiment is through the use ofbolts 2736 or other types of fasteners. In another example, rather thana flat gasket 2703, compliant elements are placed in or molded in eitherthe pressure delivery block 170 or the pressure distribution manifold172. Alternatively, the pressure delivery block 170 may be bonded to thepressure distribution manifold 172 by an adhesive, double sided tape,friction welding, laser welding, or other bonding method. The block 170and manifold 172 may be formed of metal or plastic and the bondingmethods will vary depending on the material.

The pressure distribution manifold 172 contains ports for the pneumaticvalves 2710, reference chambers 174, a fluid trap 1722 and pneumaticcircuitry or of the integrated module 2700. connections providespneumatic connections between the pressure reservoirs, valves, andcontains ports 2714 that receive multiple cartridge valves 2710. Thecartridge valves 2710 includes but is not limited to the binary valves2660 controlling flow to valve control volumes 171A, the binary valvesX1A, X1B, X2, X3 controlling flow to pump control volumes 171B, and thebinary valves 2661-2667 controlling flow to the bladders 2630, 2640,2650 and pressure reservoirs 2610, 2620. The cartridge valves 2710 arepressed into the valve ports 2714 and electrically connected to thehardware interface 310 via circuit board 2712.

The pneumatic circuitry in the pressure distribution manifold 172 may beformed with a combination of grooves or slots 1721 on the front and backfaces and approximately perpendicular holes that connect the grooves1721 on one face to valve ports 2714, the fluid trap 1722 and to groovesand ports on the opposite face. Some grooves 1721 may connect directlyto the reference chambers 174. A single perpendicular hole may connect agroove 1721 to multiple valve ports 174 that are closely spaced andstaggered. Sealed pneumatic conduits are formed when the grooves 1721are isolated from one another by in one example the front flat gasket2703 as shown in FIG. 37A.

The presence of liquid in the fluid trap 1722 may be detected by a pairof conductivity probes 2732. The conductivity probes 2732 slide througha back gasket 2704, a back plate 2730 and holes 2750 before entering thefluid trap 1722 in the pressure distribution manifold 172. The backplate 2730 seals the reference volumes 174, the grooves 1721 on the backface of the pressure distribution manifold 172 and provides ports forthe pressure sensors 2740 and ports for pressure and vacuum lines 2734and vents to the atmosphere 2732. In one example, the pressure sensorsmay be IC chips soldered to a single board 2740 and pressed as a groupagainst the back gasket 2704 on the back plate 2730. In one example,bolts 2736 clamp the back plate 2730, pressure distribution manifold 172and pressure delivery block 170 together with gaskets 2703, 2702 betweenthem. In another example, the back plate 2730 may be bonded to thepressure delivery manifold 172 as described above. The assembledintegrated module 2700 is presented in FIG. 37C.

FIG. 37C presents a schematic of the pneumatic circuit in the integratedmanifold 2700 and pneumatic elements outside the manifold. The pump 2600produces vacuum and pressure.

The pump 2600 is connected via 3 way valves 2664 and 2665 to a vent 2680and the negative or vacuum reservoir 2610 and the positive reservoir2620. The pressure in the positive and negative reservoirs 2620, 2610are measure respectively by pressure sensors 2678, 2676. The hardwareinterface 310 controls the speed of the pump 2600 and the position of3-way valves 2664, 2665, 2666 to control the pressure in each reservoir.The autoconnect stripper element bladder 2630 is connected via 3-wayvalve 2661 to either the positive pressure line 2622 or the negative orvacuum line 2612. The automation computer 300 commands the position ofvalve 2661 to control the location of the stripper element 1461. Theoccluder bladder 2640 and piston bladder 2650 are connected via 3-wayvalves 2662 and 2663 to either the pressure line 2622 or vent 2680. Theautomation computer 300 commands valve 2663 to connect the pistonbladder to the pressure line 2622 after the door 141 is closed tosecurely engage the cassette 24 against the control surface 148. Theoccluder bladder 2640 is connected to the pressure line 2622 via valve2662 and restriction 2682. The occluder bladder 2640 is connected to thevent 2680 via valve 2662. The orifice 2682 advantageously slows thefilling of the occluder bladder 2640 that retracts the occluder 147 inorder to maintain the pressure in the pressure line 2622. The highpressure in the pressure line 2622 keeps the various valve controlsurfaces 171A and the piston bladder actuated against the cassette 24,which prevents flow to or from the patient as the occluder 147 opens.Conversely the connection from the occluder bladder 2640 to the vent2680 is unrestricted, so that occluder 147 can quickly close.

The valve control surfaces 1481 are controlled by the pressure in thevalve control volume 171A, which in turn is controlled by the positionof the 3-way valves 2660. The valves 2660 can be controlled individuallyvia commands from the automation computer 300 passed to the hardwareinterface 310. The valves controlling the pumping pressures in the pumpcontrol volumes 171B are controlled with 2-way valves X1A, X1B. Thevalves X1A, X1B in one example may be controlled by the hardwareinterface 310 to achieve a pressure commanded by the automation computer300. The pressure in each pump control chamber 171B is measured bysensors 2672. The pressure in the reference chambers is measured bysensors 2670. The 2-way valves X2, X3 respectively connect the referencechamber 174 to the pump control chamber 171B and the vent 2680.

The fluid trap 2622 is to the vacuum line 2612 during operation asexplained elsewhere in this application. The fluid trap is connected byseveral lines to the ports 173B in the pressure delivery block 170. Thepressure in the fluid trap is monitored by pressure sensor 2674 that ismounted on the back plate 2730.

The vacuum ports 1483 may be employed to separate the membrane 15 fromthe control surface 148 at the end of therapy before or during theopening the door. The vacuum provided by the negative pressure source tothe vacuum ports 1483 sealingly engages the membrane 15 to the controlsurface 148 during therapy. In some instances a substantial amount offorce may be needed to separate the control surface from the cassettemembrane 15, preventing the door 141 from freely rotating into the openposition, even when the application of vacuum is discontinued. Thus, inan embodiment, the pressure distribution module 2700 is configured toprovide a valved channel between the positive pressure source and thevacuum ports 1483. Supplying positive pressure at the vacuum ports mayaid in separating the membrane 15 from the control surface 148, therebyallowing the cassette 24 to separate more easily from the controlsurface 148 and allow the door 141 to open freely. The pneumatic valvesin the cycler may be controlled by the automation computer 300 toprovide a positive pressure to the vacuum ports 1483. The manifold 172may include a separately valved channel dedicated for this purpose, oralternatively it may employ the existing channel configurations andvalves, operated in a particular sequence.

In one example the vacuum ports 1483 may be supplied with positivepressure by temporarily connecting the vacuum ports 1483 to the positivepressure reservoir 2620. The vacuum ports 1483 are normally connected tothe vacuum reservoir 2610 via a common fluid collection chamber or FluidTrap 1722 in the manifold 172 during therapy. In one example, thecontroller or automation computer may open valve X1B between thepositive pressure reservoir and the volume control chamber 171B and thevalve X1A between the negative pressure reservoir and the same volumecontrol chamber 171B simultaneously, which will pressurize the air inthe Fluid Trap 1722 and the vacuum ports 1483. The pressurized air willflow through the vacuum ports 1483 and between the membrane 15 and thecontrol surface 148, breaking any vacuum bond between the membrane andcontrol surface. However, in the illustrated manifold, the stripperelement 1491 of the cap stripper 149 may extend while the positivepressure is supplied to common fluid collection chamber 1722 fluid,because the stripper bladder 2630 is connected to a the vacuum supplyline 2612. In this example, in a subsequent step, the fluid trap 1722may be valved off from the now-pressurized vacuum line and the twovalves X1A, X1B connecting the positive and vacuum reservoirs to thevolume control chamber 171B may be closed. The vacuum pump 2600 is thenoperated to reduce the pressure in the vacuum reservoir 2610 and thevacuum supply line 2612, which in turn allows the stripper element 1491to be withdrawn. The door 141 may then be opened after detaching thecassette 24 from the control surface 148 and retracting the stripperelement 1491.

In accordance with an aspect of the invention, the vacuum ports 1483 maybe used to detect leaks in the membrane 15, e.g., a liquid sensor in aconduit or chamber connected to a vacuum port 1483 may detect liquid ifthe membrane 15 is perforated or liquid otherwise is introduced betweenthe membrane 15 and the control surface 148. For example, vacuum ports1483 may align with and be sealingly associated with complementaryvacuum ports 173B in mating block 170, which in turn may be sealinglyassociated with fluid passages 1721 leading to a common fluid collectionchamber 1722 in manifold 172. The fluid collection chamber 1722 maycontain an inlet through which vacuum can be applied and distributed toall vacuum ports 1483 of control surface 148. By applying vacuum to thefluid collection chamber 1722, fluid may be drawn from each of thevacuum ports 173B and 1483, thus removing fluid from any space betweenthe membrane 15 and the control surface 148 at the various controlregions. However, if there is liquid present at one or more of theregions, the associated vacuum port 1483 may draw the liquid into thevacuum ports 173B and into the lines 1721 leading to the fluidcollection chamber 1722. Any such liquid may collect in the fluidcollection chamber 1722, and be detected by one or more suitablesensors, e.g., a pair of conductivity sensors that detect a change inconductivity in the chamber 1722 indicating the presence of liquid. Inthis embodiment, the sensors may be located at a bottom side of thefluid collection chamber 1722, while a vacuum source connects to thechamber 1722 at an upper end of the chamber 1722. Therefore, if liquidis drawn into the fluid collection chamber 1722, the liquid may bedetected before the liquid level reaches the vacuum source. Optionally,a hydrophobic filter, valve or other component may be place at thevacuum source connection point into the chamber 1722 to help furtherresist the entry of liquid into the vacuum source. In this way, a liquidleak may be detected and acted upon by controller 16 (e.g., generatingan alert, closing liquid inlet valves and ceasing pumping operations)before the vacuum source valve is placed at risk of being contaminatedby the liquid.

In one embodiment, the inner wall of the control chambers 171B caninclude raised elements somewhat analogous to the spacer elements 50 ofthe pump chamber, e.g., as shown in FIG. 37 for the control chambers171B associated with the pump control regions 1482. These raisedelements can take the form of plateau features, ribs, or otherprotrusions that keep the control ports recessed away from the fullyretracted control regions 1482. This arrangement may allow for a moreuniform distribution of pressure or vacuum in the control chamber 171B,and prevent premature blocking of any control port by the controlsurface 148. A pre-formed control surface 148 (at least in the pumpcontrol regions) may not be under a significant stretching force whenfully extended against either the inner wall of the pump chamber of thecassette 24 during a delivery stroke, or the inner wall of the controlchamber 171 during a fill stroke. It may therefore be possible for thecontrol region 1482 to extend asymmetrically into the control chamber171B, causing the control region 1482 to prematurely close off one ormore ports of the control chamber before the chamber is fully evacuated.Having features on the inner surface of the control chamber 171B thatprevent contact between the control region 1482 and the control portsmay help to assure that the control region 1482 can make uniform contactwith the control chamber inner wall during a fill stroke.

As suggested above, the cycler 14 may include a control system 16 with adata processor in electrical communication with the various valves,pressure sensors, motors, etc., of the system and is preferablyconfigured to control such components according to a desired operatingsequence or protocol. The control system 16 may include appropriatecircuitry, programming, computer memory, electrical connections, and/orother components to perform a specified task. The system may includepumps, tanks, manifolds, valves or other components to generate desiredair or other fluid pressure (whether positive pressure—above atmosphericpressure or some other reference—or negative pressure or vacuum—belowatmospheric pressure or some other reference) to control operation ofthe regions of the control surface 148, and other pneumatically-operatedcomponents. Further details regarding the control system 16 (or at leastportions of it) are provided below.

In one illustrative embodiment, the pressure in the pump controlchambers 171B may be controlled by a binary valve, e.g., which opens toexpose the control chamber 171 to a suitable pressure/vacuum and closesto cut off the pressure/vacuum source. The binary valve may becontrolled using a saw tooth-shaped control signal which may bemodulated to control pressure in the pump control chamber 171B. Forexample, during a pump delivery stroke (i.e., in which positive pressureis introduced into the pump control chamber 171B to move the membrane15/control surface 148 and force liquid out of the pump chamber 181),the binary valve may be driven by the saw tooth signal so as to open andclose at a relatively rapid rate to establish a suitable pressure in thecontrol chamber 171B (e.g., a pressure between about 70-90 mmHg). If thepressure in the control chamber 171B rises above about 90 mmHg, the sawtooth signal may be adjusted to close the binary valve for a moreextended period. If the pressure drops below about 70 mmHg in thecontrol chamber 171B, the saw tooth control signal may again be appliedto the binary valve to raise the pressure in the control chamber 171.Thus, during a typical pump operation, the binary valve will be openedand closed multiple times, and may be closed for one or more extendedperiods, so that the pressure at which the liquid is forced from thepump chamber 181 is maintained at a desired level or range (e.g., about70-90 mmHg).

In some embodiments and in accordance with an aspect of the invention,it may be useful to detect an “end of stroke” of the membrane 15/pumpcontrol region 1482, e.g., when the membrane 15 contacts the spacers 50in the pump chamber 181 or the pump control region 1482 contacts thewall of the pump control chamber 171B. For example, during a pumpingoperation, detection of the “end of stroke” may indicate that themembrane 15/pump control region 1482 movement should be reversed toinitiate a new pump cycle (to fill the pump chamber 181 or drive fluidfrom the pump chamber 181). In one illustrative embodiment in which thepressure in the control chamber 171B for a pump is controlled by abinary valve driven by a saw tooth control signal, the pressure in thepump chamber 181 will fluctuate at a relatively high frequency, e.g., afrequency at or near the frequency at which the binary valve is openedand closed. A pressure sensor in the control chamber 171B may detectthis fluctuation, which generally has a higher amplitude when themembrane 15/pump control region 1482 are not in contact with the innerwall of the pump chamber 181 or the wall of the pump control chamber171B. However, once the membrane 15/pump control region 1482 contactsthe inner wall of the pump chamber 181 or the wall of the pump controlchamber 171B (i.e., the “end of stroke”), the pressure fluctuation isgenerally damped or otherwise changes in a way that is detectable by thepressure sensor in the pump control chamber 171B. This change inpressure fluctuation can be used to identify the end of stroke, and thepump and other components of the cassette 24 and/or cycler 14 may becontrolled accordingly.

In one embodiment, the pneumatic pressure applied to the control chamber171B is actively controlled by a processor receiving a signal from apressure transducer 2672 (FIG. 37C) connected to the control chamber171B and a fast acting binary valve X1A, X1B between a pressurereservoir 2620, 2610 and the control chamber 171B. The processor maycontrol the pressure with a variety of control algorithms includingclosed loop proportional or proportional-integrator feedback controlthat varies the valve duty cycle to achieve the desired pressure in thecontrol volume 171B. In a one embodiment, the processor controls thepressure in the control chamber with an on-off controller often called abang-bang controller. The on-off controller monitors the pressure in thecontrol volume 171B during a deliver stroke and open the binary valveX1B (connecting the control volume 171B to the positive reservoir 2620)when the pressure is less than a lower first limit and closes the binaryvalve X1B when the pressure is above a higher second limit. During afill stroke, the on-off controller opens the binary valve X1A(connecting the control volume 171B to the negative reservoir 2610) whenthe pressure is greater than a third limit and closes the binary valveX1A when the pressure is less than a forth limit, where the forth limitis lower than the third limit and both the third and forth limits areless than the first limit. A plot of the pressure over time as during adeliver stroke and the subsequent FMS measurement is shown in FIG. 66.The control chamber pressure 2300 oscillates between the lower firstlimit 2312 and the higher second limit 2310 as the membrane 15 movesacross the control chamber 171B. The pressure stops oscillating betweenthe limits when the membrane 15 stops moving. The membrane 15 typicallystops moving when it contacts either the stadium steps 50 of thecassette or it contacts the control chamber surface 171B. The membrane15 may also stop moving if the outlet fluid line is occluded.

The automation computer 300 detects the end of stroke by evaluating thepressure signals. There are many possible algorithms to detect the endof pressure oscillation that indicate the end-of-stroke (EOS). Thealgorithms and methods to detect EOS in the section labeled “DetailedDescription of the system and Method of Measuring Change Fluid FlowRate” in U.S. Pat. No. 6,520,747 and the section describing thefiltering to detect end of stroke in U.S. Pat. No. 8,292,594 are hereinincorporated by reference.

One example of an algorithm to detect EOS, the AC 300 evaluates the timebetween the pressure crossing the first and second limits during adeliver stroke or third and fourth limits during a fill stroke. Theon-off controller opens and closes the valves X1A, X1B in response tothe pressure oscillating between the two limits as the control chambervolume changes during the fill or deliver stroke. When the membrane 15stops moving at the end-of-stroke, the pressure changes willsignificantly diminish so that the pressure no longer exceeds one orboth limits. The AC 300 may detect EOS by measuring the time between thepressure exceeding alternating limits. If the time since pressure crossthe last limit exceeds a predefined threshold, then the AC 300 maydeclare an EOS. The algorithm may further include an initial periodduring which the AC 300 does not measure the time between limitcrossings.

In another example algorithm, the AC 300 evaluates the derivative of thepressure signal with respect to time. The AC 300 may declare an EOS, ifthe derivative remains below a minimum threshold for a minimum length oftime. In a further example, the minimum threshold is the average of theabsolute value of the average pressure derivative during the stroke. Thealgorithm calculates the slope (derivative wrt time) of a curve fit to aset of data points, where the data points are taken from a movingwindow. The absolute value of each slope is then averaged over thestroke to calculate the absolute a value of the average pressurederivative. In another example of an EOS algorithm, the AC 300 may notinclude the pressure data until after an initial delay. The AC 300ignores the initial pressure data to avoid false EOS detections due toirregular pressure traces that occasionally occur during the early partof the stroke. In another example, the AC 300 declares an EOS only afterthe second derivative of the pressure in the later part of the strokehas remained below a threshold for a minimum time and a wait period oftime has past.

The criteria to declare an EOS may be optimized for different pumpingconditions. The optimized EOS detection conditions include the secondpressure derivative threshold, the minimum time to remain below thesecond derivative threshold, the duration of the initial delay and alength of the wait period. These EOS detection criteria may be optimizeddifferently, for example, the fill stroke from the bags 20,22, thedeliver stroke to the patient, the fill stroke from the patient, and thedeliver stroke to the bags 20,22. Alternatively each EOS detectioncriteria may be a function of the pumping pressure in the controlchamber 171B.

Occluder In one aspect of the invention, an occluder for opening/closingone or more flexible lines may include a pair of opposed occludingmembers, which may be configured as resilient elements, such as flatplates made of a spring steel (e.g., leaf springs), having a forceactuator configured to apply a force to one or both of the occludingmembers to operate the occluder. In certain embodiments, the forceactuator may comprise an expandable or enlargable member positionedbetween the resilient elements. With the expandable member in a reducedsize condition, the resilient elements may be in a flat or nearly flatcondition and urge a pinch head to engage with one or more lines so asto pinch the lines closed. However, when the expandable member urges theresilient elements apart, the resilient elements may bend and withdrawthe pinch head, releasing the lines and allowing flow through the lines.In other embodiments, the occluding members could be essentially rigidwith respect to the levels of force applied by the force actuator. Incertain embodiments, the force actuator may apply a force to one or bothopposed occluding members to increase the distance between the occludingmembers in at least a portion of the region where they are opposed toeffect opening or closing of the flexible tubing.

FIG. 38 shows an exploded view and FIG. 39 shows a partially assembledview of an illustrative embodiment of an occluder 147 that may be usedto close, or occlude, the patient and drain lines 34 and 28, and/orother lines in the cycler 14 or the set 12 (such as, for example, theheater bag line 26). The occluder 147 includes an optional pinch head161, e.g., a generally flat blade-like element that contacts the tubesto press the tubes against the door 141 and pinch the tubes closed. Inother embodiments, the function of the pinch head could be replaced byan extending edge of one or both of occluding members 165. The pinchhead 161 includes a gasket 162, such as an O-ring or other member, thatcooperates with the pinch head 161 to help resist entry of fluid (air orliquid for example) into the cycler 14 housing, e.g., in case of leakagein one of the occluded lines. The bellows gasket 162 is mounted to, andpinch head 161 passes through, a pinch head guide 163 that is mounted tothe front panel of the cycler housing, i.e., the panel exposed byopening the door 141. The pinch head guide 163 allows the pinch head 161to move in and out of the pinch head guide 163 without binding and/orsubstantial resistance to sliding motion of the pinch head 161. A pivotshaft 164 attaches a pair of opposed occluder members, comprising in theillustrated embodiment spring plates 165, that each include ahook-shaped pivot shaft bearing, e.g., like that found on standard doorhinges, to the pinch head 161. That is, the openings of shaft guides onthe pinch head 161, and the openings formed by the hook-shaped bearingson the spring plates 165 are aligned with each other and the pivot shaft164 is inserted through the openings so the pinch head 161 and thespring plates 165 are pivotally connected together. The spring plates165 may be made of any suitable material, such as steel, and may bearranged to be generally flat when unstressed. The opposite end of thespring plates 165 includes similar hook-shaped bearings, which arepivotally connected to a linear adjustor 167 by a second pivot shaft164. In this embodiment, the force actuator comprises a bladder 166 ispositioned between the spring plates 165 and arranged so that when fluid(e.g., air under pressure) is introduced into the bladder, the bladdermay expand and push the spring plates 165 away from each other in aregion between the pivot shafts 164. The bladder 166 may be attached toone or both spring plates 165 by pressure sensitive adhesive (PSA) tape.A linear adjustor 167 is fixed to the cycler housing 82 while the pinchhead 161 is allowed to float, although its movement is guided by thepinch head guide 163. The linear adjustor 167 includes slot holes at itslower end, allowing the entire assembly to be adjusted in position andthus permitting the pinch head to be appropriately positioned when theoccluder 147 is installed in the cycler 14. A turnbuckle 168 or otherarrangement may be used to help adjust the position of the linearadjustor 167 relative to the housing 82. That is, the pinch head 161generally needs to be properly positioned so that with the spring plates165 located near each other and the bladder 166 substantially emptied orat ambient pressure, the pinch head 161 suitably presses on the patientand drain lines so as to pinch the tubes closed to flow without cutting,kinking or otherwise damaging the tubes. The slot openings in the linearadjustor 167 allows for this fine positioning and fixing of the occluder147 in place. An override release device, such as provided by releaseblade 169 is optionally positioned between the spring plates 165, and asis discussed in more detail below, may be rotated so as to push thespring plates 165 apart, thereby withdrawing the pinch head 161 into thepinch head guide 163. The release blade 169 may be manually operated,e.g., to disable the occluder 147 in case of power loss, bladder 166failure or other circumstance.

Additional configurations and descriptions of certain components thatmay be instructive in constructing certain embodiments of the occluderare provided in U.S. Pat. No. 6,302,653. The spring plates 165 may beconstructed from any material that is elastically resistant to bendingforces and which has sufficient longitudinal stiffness (resistance tobending) to provide sufficient restoring force, in response to a bendingdisplacement, to occlude a desired number of collapsible tubes. In theillustrated embodiment, each spring plate is essentially flat whenunstressed and in the shape of a sheet or plate. In alternativeembodiments utilizing one or more resilient occluding members (springmembers), any occluding member(s) that is elastically resistant tobending forces and which has sufficient longitudinal stiffness(resistance to bending) to provide sufficient restoring force, inresponse to a bending displacement to occlude a desired number ofcollapsible tubes may be utilized. Potentially suitable spring memberscan have a wide variety of shapes as apparent to those of ordinary skillin the art, including, but not limited to cylindrical, prism-shaped,trapezoidal, square, or rectangular bars or beams, I-beams, ellipticalbeams, bowl-shaped surfaces, and others. Those of ordinary skill in theart can readily select proper materials and dimensions for spring plates165 based on the present teachings and the requirements of a particularapplication.

FIG. 40 shows a top view of the occluder 147 with the bladder 166deflated and the spring plates 165 located near each other and in a flator nearly flat condition. In this position, the pinch head 161 is fullyextended from the pinch head guide and the front panel of the cycler 14(i.e., the panel inside of the door 141) and enabled to occlude thepatient and drain lines. FIG. 41, on the other hand, shows the bladder166 in an inflated state in which the spring plates 165 are pushedapart, thereby retracting the pinch head 161 into the pinch head guide163. (Note that the linear adjustor 167 is fixed in place relative tothe cycler housing 82 and thus fixed relative to the front panel of thehousing 82. As the spring plates 165 are moved apart, the pinch head 161moves rearwardly relative to the front panel since the pinch head 161 isarranged to move freely in and out of the pinch head guide 163.) Thiscondition prevents the pinch head 161 from occluding the patient anddrain lines and is the condition in which the occluder 147 remainsduring normal operation of the cycler 14. That is, as discussed above,various components of the cycler 14 may operate using airpressure/vacuum, e.g., the control surface 148 may operate under thedrive of suitable air pressure/vacuum to cause fluid pumping and valveoperation for the cassette 24. Thus, when the cycler 14 is operatingnormally, the cycler 14 may produce sufficient air pressure to not onlycontrol system operation, but also to inflate the bladder 166 to retractthe pinch head 161 and prevent occlusion of the patient and drain lines.However, in the case of system shut down, failure, fault or othercondition, air pressure to the bladder 166 may be terminated, causingthe bladder 166 to deflate and the spring plates 165 to straighten andextend the pinch head 161 to occlude the lines. One possible advantageof the arrangement shown is that the return force of the spring plates165 is balanced such that the pinch head 161 generally will not bind inthe pinch head guide 163 when moving relative to the pinch head guide163. In addition, the opposing forces of the spring plates 165 will tendto reduce the amount of asymmetrical frictional wear of the pivot shaftsand bushings of the assembly. Also, once the spring plates 165 are in anapproximately straight position, the spring plates 165 can exert a forcein a direction generally along the length of the pinch head 161 that isseveral times larger than the force exerted by the bladder 166 on thespring plates 165 to separate the spring plates 165 from each other andretract the pinch head 161. Further, with the spring plates 165 in aflat or nearly flat condition, the force needed to be exerted by fluidin the collapsed tubing to overcome the pinching force exerted by thepinch head 161 approaches a relatively high force required, when appliedto the spring plates at their ends and essentially parallel to the planeof the flattened spring plates, to buckle the spring plates by breakingthe column stability of the flattened spring plates. As a result, theoccluder 147 can be very effective in occluding the lines with a reducedchance of failure while also requiring a relatively small force beapplied by the bladder 166 to retract the pinch head 161. The dualspring plate arrangement of the illustrative embodiment may have theadditional advantage of significantly increasing the pinching forceprovided by the pinch head, for any given force needed to bend thespring plate, and/or for any given size and thickness of spring plate.

In some circumstances, the force of the occluder 147 on the lines may berelatively large and may cause the door 141 to be difficult to open.That is, the door 141 must oppose the force of the occluder 147 when thepinch head 161 is in contact with and occluding lines, and in some casesthis may cause the latch that maintains the door 141 in a closed stateto be difficult or impossible to operate by hand. Of course, if thecycler 14 is started and produces air pressure to operate, the occluderbladder 166 can be inflated and the occluder pinch head 161 retracted.However, in some cases, such as with a pump failure in the cycler 14,inflation of the bladder 166 may be impossible or difficult. To allowopening of the door, the occluder 147 may include a manual release. Inthis illustrative embodiment, the occluder 147 may include a releaseblade 169 as shown in FIGS. 38 and 39 which includes a pair of wingspivotally mounted for rotary movement between the spring plates 165.When at rest, the release blade wings may be aligned with the springs asshown in FIG. 39, allowing the occluder to operate normally. However, ifthe spring plates 165 are in a flat condition and the pinch head 161needs to be retracted manually, the release blade 169 may be rotated,e.g., by engaging a hex key or other tool with the release blade 169 andturning the release blade 169, so that the wings push the spring plates165 apart. The hex key or other tool may be inserted through an openingin the housing 82 of the cycler 14, e.g., an opening near the left sidehandle depression in the cycler housing 82, and operated to disengagethe occluder 147 and allow the door 141 to be opened.

Pump Volume Delivery Measurement

In another aspect of the invention, the cycler 14 may determine a volumeof fluid delivered in various lines of the system 10 without the use ofa flowmeter, weight scale or other direct measurement of fluid volume orweight. For example, in one embodiment, a volume of fluid moved by apump, such as a pump in the cassette 24, may be determined based onpressure measurements of a gas used to drive the pump. In oneembodiment, a volume determination can be made by isolating two chambersfrom each other, measuring the respective pressures in the isolatedchambers, allowing the pressures in the chambers to partially orsubstantially equalize (by fluidly connecting the two chambers) andmeasuring the pressures. Using the measured pressures, the known volumeof one of the chambers, and an assumption that the equalization occursin an adiabatic way, the volume of the other chamber (e.g., a pumpchamber) can be calculated. In one embodiment, the pressures measuredafter the chambers are fluidly connected may be substantially unequal toeach other, i.e., the pressures in the chambers may not have yetcompletely equalized. However, these substantially unequal pressures maybe used to determine a volume of the pump control chamber, as explainedbelow.

For example, FIG. 42 shows a schematic view of a pump chamber 181 of thecassette 24 and associated control components and inflow/outflow paths.In this illustrative example, a liquid supply, which may include theheater bag 22, heater bag line 26 and a flow path through the cassette24, is shown providing a liquid input at the upper opening 191 of thepump chamber. The liquid outlet is shown in this example as receivingliquid from the lower opening 187 of the pump chamber 181, and mayinclude a flow path of the cassette 24 and the patient line 34, forexample. The liquid supply may include a valve, e.g., including thevalve port 192, that can be opened and closed to permit/impede flow toor from the pump chamber 181. Similarly, the liquid outlet may include avalve, e.g., including the valve port 190, that can be opened and closedto permit/impede flow to or from the pump chamber 181. Of course, theliquid supply could include any suitable arrangement, such as one ormore solution containers, the patient line, one or more flow paths inthe cassette 24 or other liquid source, and the liquid outlet couldlikewise include any suitable arrangement, such as the drain line, theheater bag and heater bag line, one or more flow paths in the cassette24 or other liquid outlet. Generally speaking, the pump chamber 181(i.e., on the left side of the membrane 14 in FIG. 42) will be filledwith an incompressible liquid, such as water or dialysate, duringoperation. However, air or other gas may be present in the pump chamber181 in some circumstances, such as during initial operation, priming, orother situations as discussed below. Also, it should be understood thatalthough aspects of the invention relating to volume and/or pressuredetection for a pump are described with reference to the pumparrangement of the cassette 24, aspects of the invention may be usedwith any suitable pump or fluid movement system.

FIG. 42 also shows schematically to the right of the membrane 15 and thecontrol surface 1482 (which are adjacent each other) a control chamber171B, which may be formed as a void or other space in the mating block170A associated with the pump control region 1482 of the control surface1482 for the pump chamber 181, as discussed above. It is in the controlchamber 171B that suitable air pressure is introduced to cause themembrane 15/control region 1482 to move and effect pumping of liquid inthe pump chamber 181. The control chamber 171B may communicate with aline L0 that branches to another line L1 and a first valve X1 thatcommunicates with a pressure source 84 (e.g., a source of air pressureor vacuum). The pressure source 84 may include a piston pump in whichthe piston is moved in a chamber to control a pressure delivered to thecontrol chamber 171B, or may include a different type of pressure pumpand/or tank(s) to deliver suitable gas pressure to move the membrane15/control region 1482 and perform pumping action. The line L0 alsoleads to a second valve X2 that communicates with another line L2 and areference chamber 174 (e.g., a space suitably configured for performingthe measurements described below). The reference chamber 174 alsocommunicates with a line L3 having a valve X3 that leads to a vent orother reference pressure (e.g., a source of atmospheric pressure orother reference pressure). Each of the valves X1, X2 and X3 may beindependently controlled. Pressure sensors may be arranged, e.g., onesensor at the control chamber 171B and another sensor at the referencechamber 174, to measure pressure associated with the control chamber andthe reference chamber. These pressure sensors may be positioned and mayoperate to detect pressure in any suitable way. The pressure sensors maycommunicate with the control system 16 for the cycler 14 or othersuitable processor for determining a volume delivered by the pump orother features.

As mentioned above, the valves and other components of the pump systemshown in FIG. 42 can be controlled so as to measure pressures in thepump chamber 181, the liquid supply and/or liquid outlet, and/or tomeasure a volume of fluid delivered from the pump chamber 181 to theliquid supply or liquid outlet. Regarding volume measurement, onetechnique used to determine a volume of fluid delivered from the pumpchamber 181 is to compare the relative pressures at the control chamber171B to that of the reference chamber 174 in two different pump states.By comparing the relative pressures, a change in volume at the controlchamber 171B can be determined, which corresponds to a change in volumein the pump chamber 181 and reflects a volume delivered from/receivedinto the pump chamber 181. For example, after the pressure is reduced inthe control chamber 171B during a pump chamber fill cycle (e.g., byapplying negative pressure from the pressure source through open valveX1) so as to draw the membrane 15 and pump control region 1482 intocontact with at least a portion of the control chamber wall (or toanother suitable position for the membrane 15/region 1482), valve X1 maybe closed to isolate the control chamber from the pressure source, andvalve X2 may be closed, thereby isolating the reference chamber 174 fromthe control chamber 171B. Valve X3 may be opened to vent the referencechamber to ambient pressure, then closed to isolate the referencechamber. With valve X1 closed and the pressures in the control chamberand reference chamber measured, valve X2 is then opened to allow thepressure in the control chamber and the reference chamber to start toequalize. The initial pressures of the reference chamber and the controlchamber, together with the known volume of the reference chamber andpressures measured after equalization has been initiated (but not yetnecessarily completed) can be used to determine a volume for the controlchamber. This process may be repeated at the end of the pump deliverycycle when the sheet 15/control region 1482 are pushed into contact withthe spacer elements 50 of the pump chamber 181. By comparing the controlchamber volume at the end of the fill cycle to the volume at the end ofthe delivery cycle, a volume of liquid delivered from the pump can bedetermined.

Conceptually, the pressure equalization process (e.g., at opening of thevalve X2) is viewed as happening in an adiabatic way, i.e., without heattransfer occurring between air in the control and reference chambers andits environment. The conceptual notion is that there is an imaginarypiston located initially at the valve X2 when the valve X2 is closed,and that the imaginary piston moves in the line L0 or L2 when the valveX2 is opened to equalize the pressure in the control and referencechambers. Since (a) the pressure equalization process happens relativelyquickly, (b) the air in the control chamber and the reference chamberhas approximately the same concentrations of elements, and (c) thetemperatures are similar, the assumption that the pressure equalizationhappens in an adiabatic way may introduce only small error into thevolume measurements. Also, in one embodiment, the pressures taken afterequalization has been initiated may be measured before substantialequalization has occurred—further reducing the time between measuringthe initial pressures and the final pressures used to determine the pumpchamber volume. Error can be further reduced, for example, by using lowthermal conductivity materials for the membrane 15/control surface 1482,the cassette 24, the control chamber 171B, the lines, the referencechamber 174, etc., so as to reduce heat transfer.

Given the assumption that an adiabatic system exists between the statewhen the valve X2 is closed until after the valve X2 is opened and thepressures equalize, the following applies:

PV ^(γ)=Constant  (1)

where P is pressure, V is volume and γ is equal to a constant (e.g.,about 1.4 where the gas is diatomic, such as air). Thus, the followingequation can be written to relate the pressures and volumes in thecontrol chamber and the reference chamber before and after the openingof valve X2 and pressure equalization occurs:

PrVr ^(γ) +PdVd ^(γ)=Constant=PfVf ^(γ)  (2)

where Pr is the pressure in the reference chamber and lines L2 and L3prior to the valve X2 opening, Vr is the volume of the reference chamberand lines L2 and L3 prior to the valve X2 opening, Pd is the pressure inthe control chamber and the lines L0 and L1 prior to the valve X2opening, Vd is the volume of the control chamber and the lines L0 and L1prior to the valve X2 opening, Pf is the equalized pressure in thereference chamber and the control chamber after opening of the valve X2,and Vf is the volume of the entire system including the control chamber,the reference chamber and the lines L0, L1, L2, and L3, i.e., Vf=Vd+Vr.Since Pr, Vr, Pd, Pf and γ are known, and Vf=Vr+Vd, this equation can beused to solve for Vd. (Although reference is made herein, including inthe claims, to use of a “measured pressure” in determining volumevalues, etc., it should be understood that such a measured pressurevalue need not necessarily be any particular form, such as in psi units.Instead, a “measured pressure” or “determined pressure” may include anyvalue that is representative of a pressure, such as a voltage level, aresistance value, a multibit digital number, etc. For example, apressure transducer used to measure pressure in the pump control chambermay output an analog voltage level, resistance or other indication thatis representative of the pressure in the pump control chamber. The rawoutput from the transducer may be used as a measured pressure, and/orsome modified form of the output, such as a digital number generatedusing an analog output from the transducer, a psi or other value that isgenerated based on the transducer output, and so on. The same is true ofother values, such as a determined volume, which need not necessarily bein a particular form such as cubic centimeters. Instead, a determinedvolume may include any value that is representative of the volume, e.g.,could be used to generate an actual volume in, say, cubic centimeters.)

In an embodiment of a fluid management system (“FMS”) technique todetermine a volume delivered by the pump, it is assumed that pressureequalization upon opening of the valve X2 occurs in an adiabatic system.Thus, Equation 3 below gives the relationship of the volume of thereference chamber system before and after pressure equalization:

Vrf=Vri(Pf/Patm)^(−(1/γ))  (3)

where Vrf is the final (post-equalization) volume of the referencechamber system including the volume of the reference chamber, the volumeof the lines L2 and L3 and the volume adjustment resulting from movementof the “piston”, which may move to the left or right of the valve X2after opening, Vri is the initial (pre-equalization) volume of thereference chamber and the lines L2 and L3 with the “piston” located atthe valve X2, Pf is the final equalized pressure after the valve X2 isopened, and Patm is the initial pressure of the reference chamber beforevalve X2 opening (in this example, atmospheric pressure). Similarly,Equation 4 gives the relationship of the volume of the control chambersystem before and after pressure equalization:

Vdf=Vdi(Pf/Pdi)^(−(1/γ))  (4)

where Vdf is the final volume of the control chamber system includingthe volume of the control chamber, the volume of the lines L0 and L1,and the volume adjustment resulting from movement of the “piston”, whichmay move to the left or right of the valve X2 after opening, Vdi is theinitial volume of the control chamber and the lines L0 and L1 with the“piston” located at the valve X2, Pf is the final pressure after thevalve X2 is opened, and Pdi is the initial pressure of the controlchamber before valve X2 opening.

The volumes of the reference chamber system and the control chambersystem will change by the same absolute amount after the valve X2 isopened and the pressure equalizes, but will differ in sign (e.g.,because the change in volume is caused by movement of the “piston” leftor right when the valve X2 opens), as shown in Equation 5:

ΔVr=(−1)ΔVd  (5)

(Note that this change in volume for the reference chamber and thecontrol chamber is due only to movement of the imaginary piston. Thereference chamber and control chamber will not actually change in volumeduring the equalization process under normal conditions.) Also, usingthe relationship from Equation 3, the change in volume of the referencechamber system is given by:

ΔVr=Vrf−Vri=Vri(−1+(Pf/Patm)^(−(1/γ)))  (6)

Similarly, using Equation 4, the change in volume of the control chambersystem is given by:

ΔVd=Vdf−Vdi=Vdi(−1+(Pf/Pdi)^(−(1/γ)))  (7)

Because Vri is known, and Pf and Patm are measured or known, ΔVr can becalculated, which according to Equation 5 is assumed to be equal to(−)ΔVd. Therefore, Vdi (the volume of the control chamber system beforepressure equalization with the reference chamber) can be calculatedusing Equation 7. In this embodiment, Vdi represents the volume of thecontrol chamber plus lines L0 and L1, of which L0 and L1 are fixed andknown quantities. Subtracting L0 and L1 from Vdi yields the volume ofthe control chamber alone. By using Equation 7 above, for example, bothbefore (Vdi1) and after (Vdi2) a pump operation (e.g., at the end of afill cycle and at the end of a discharge cycle), the change in volume ofthe control chamber can be determined, thus providing a measurement ofthe volume of fluid delivered by (or taken in by) the pump. For example,if Vdi1 is the volume of the control chamber at the end of a fillstroke, and Vdi2 is the volume of the control chamber at the end of thesubsequent delivery stroke, the volume of fluid delivered by the pumpmay be estimated by subtracting Vdi1 from Vdi2. Since this measurementis made based on pressure, the volume determination can be made fornearly any position of the membrane 15/pump control region 1482 in thepump chamber 181, whether for a full or partial pump stroke. However,measurement made at the ends of fill and delivery strokes can beaccomplished with little or no impact on pump operation and/or flowrate.

One aspect of the invention involves a technique for identifyingpressure measurement values that are to be used in determining a volumefor the control chamber and/or other purposes. For example, althoughpressure sensors may be used to detect a pressure in the control chamberand a pressure in the reference chamber, the sensed pressure values mayvary with opening/closing of valves, introduction of pressure to thecontrol chamber, venting of the reference chamber to atmosphericpressure or other reference pressure, etc. Also, since in oneembodiment, an adiabatic system is assumed to exist from a time beforepressure equalization between the control chamber and the referencechamber until after equalization, identifying appropriate pressurevalues that were measured as close together in time may help to reduceerror (e.g., because a shorter time elapsed between pressuremeasurements may reduce the amount of heat that is exchanged in thesystem). Thus, the measured pressure values may need to be chosencarefully to help ensure appropriate pressures are used for determininga volume delivered by the pump, etc.

For purposes of explanation, FIG. 43 shows a plot of illustrativepressure values for the control chamber and the reference chamber from apoint in time before opening of the valve X2 until some time after thevalve X2 is opened to allow the pressure in the chambers to equalize. Inthis illustrative embodiment, the pressure in the control chamber ishigher than the pressure in the reference chamber before equalization,but it should be understood that the control chamber pressure may belower than the reference chamber pressure before equalization in somearrangements, such as during and/or at the end of a fill stroke. Also,the plot in FIG. 43 shows a horizontal line marking the equalizationpressure, but it should be understood that this line is shown forclarity only. The equalization pressure in general will not be knownprior to opening of the valve X2. In this embodiment, the pressuresensors sense pressure at a rate of about 2000 Hz for both the controlchamber and the reference chamber, although other suitable samplingrates could be used. Before opening of the valve X2, the pressures inthe control chamber and the reference chamber are approximatelyconstant, there being no air or other fluid being introduced into thechambers. Thus, the valves X1 and X3 will generally be closed at a timebefore opening of the valve X2. Also, valves leading into the pumpchamber, such as the valve ports 190 and 192, may be closed to preventinfluence of pressure variations in the pump chamber, the liquid supplyor liquid outlet.

At first, the measured pressure data is processed to identify theinitial pressures for the control chamber and reference chambers, i.e.,Pd and Pr. In one illustrative embodiment, the initial pressures areidentified based on analysis of a 10-point sliding window used on themeasured pressure data. This analysis involves generating a best fitline for the data in each window (or set), e.g., using a least squarestechnique, and determining a slope for the best fit line. For example,each time a new pressure is measured for the control chamber or thereference chamber, a least squares fit line may be determined for a dataset including the latest measurement and the 9 prior pressuremeasurements. This process may be repeated for several sets of pressuredata, and a determination may be made as to when the slope of the leastsquares fit lines first becomes negative (or otherwise non-zero) andcontinues to grow more negative for subsequent data sets (or otherwisedeviates from a zero slope). The point at which the least squares fitlines begin to have a suitable, and increasing, non-zero slope may beused to identify the initial pressure of the chambers, i.e., at a timebefore the valve X2 is opened.

In one embodiment, the initial pressure value for the reference chamberand the control chamber may be determined to be in the last of 5consecutive data sets, where the slope of the best fit line for the datasets increases from the first data set to the fifth data set, and theslope of the best fit line for the first data set first becomes non-zero(i.e., the slope of best fit lines for data sets preceding the firstdata set is zero or otherwise not sufficiently non-zero). For example,the pressure sensor may take samples every ½ millisecond (or othersampling rate) starting at a time before the valve X2 opens. Every timea pressure measurement is made, the cycler 14 may take the most recentmeasurement together with the prior 9 measurements, and generate a bestfit line to the 10 data points in the set. Upon taking the next pressuremeasurement (e.g., ½ millisecond later), the cycler 14 may take themeasurement together with the 9 prior measurements, and again generate abest fit line to the 10 points in the set. This process may be repeated,and the cycler 14 may determine when the slope of the best fit line fora set of 10 data points first turns non-zero (or otherwise suitablysloped) and, for example, that the slope of the best fit line for 5subsequent sets of 10 data points increases with each later data set. Toidentify the specific pressure measurement to use, one technique is toselect the third measurement in the 5^(th) data set (i.e., the 5^(th)data set with which it was found that the best fit line has beenconsistently increasing in slope and the 1^(st) measurement is thepressure measurement that was taken earliest in time) as the measurementto be used as the initial pressure for the control chamber or thereference chamber, i.e., Pd or Pr. This selection was chosen usingempirical methods, e.g., plotting the pressure measurement values andthen selecting which point best represents the time when the pressurebegan the equalization process. Of course, other techniques could beused to select the appropriate initial pressure.

In one illustrative embodiment, a check may be made that the times atwhich the selected Pd and Pr measurements occurred were within a desiredtime threshold, e.g., within 1-2 milliseconds of each other. Forexample, if the technique described above is used to analyze the controlchamber pressure and the reference chamber pressure and identify apressure measurement (and thus a point in time) just before pressureequalization began, the times at which the pressures were measuredshould be relatively close to each other. Otherwise, there may have beenan error or other fault condition that invalidates one or both of thepressure measurements. By confirming that the time at which Pd and Proccurred are suitably close together, the cycler 14 may confirm that theinitial pressures were properly identified.

To identify when the pressures in the control chamber and the referencechamber have equalized such that measured pressures for the chamber canbe used to reliably determine pump chamber volume, the cycler 14 mayanalyze data sets including a series of data points from pressuremeasurements for both the control chamber and the reference chamber,determine a best fit line for each of the data sets (e.g., using a leastsquares method), and identify when the slopes of the best fit lines fora data set for the control chamber and a data set for the referencechamber are first suitably similar to each other, e.g., the slopes areboth close to zero or have values that are within a threshold of eachother. When the slopes of the best fit lines are similar or close tozero, the pressure may be determined to be equalized. The first pressuremeasurement value for either data set may be used as the final equalizedpressure, i.e., Pf. In one illustrative embodiment, it was found thatpressure equalization occurred generally within about 200-400milliseconds after valve X2 is opened, with the bulk of equalizationoccurring within about 50 milliseconds. Accordingly, the pressure in thecontrol and reference chambers may be sampled approximately 400-800times or more during the entire equalization process from a time beforethe valve X2 is opened until a time when equalization has been achieved.

In some cases, it may be desirable to increase the accuracy of thecontrol chamber volume measurement using an alternate FMS technique.Substantial differences in temperature between the liquid being pumped,the control chamber gas, and the reference chamber gas may introducesignificant errors in calculations based on the assumption that pressureequalization occurs adiabatically. Waiting to make pressure measurementsuntil full equalization of pressure between the control chamber and thereference chamber may allow an excessive amount of heat transfer tooccur. In one aspect of the invention, pressure values for the pumpchamber and reference chamber that are substantially unequal to eachother, i.e., that are measured before complete equalization hasoccurred, may be used to determine pump chamber volume.

In one embodiment, heat transfer may be minimized, and adiabaticcalculation error reduced, by measuring the chamber pressures throughoutthe equalization period from the opening of valve X2 through fullpressure equalization, and selecting a sampling point during theequalization period for the adiabatic calculations. In one embodiment ofan APD system, measured chamber pressures that are taken prior tocomplete pressure equalization between the control chamber and thereference chamber can be used to determine pump chamber volume. In oneembodiment, these pressure values may be measured about 50 ms after thechambers are first fluidly connected and equalization is initiated. Asmentioned above, in one embodiment, complete equalization may occurabout 200-400 ms after the valve X2 is opened. Thus, the measuredpressures may be taken at a point in time after the valve X2 is opened(or equalization is initiated) that is about 10% to 50% or less of thetotal equalization time period. Said another way, the measured pressuresmay be taken at a point in time at which 50-70% of pressure equalizationhas occurred (i.e., the reference and pump chamber pressures havechanged by about 50-70% of the difference between the initial chamberpressure and the final equalized pressure. Using a computer-enabledcontroller, a substantial number of pressure measurements in the controland reference chambers can be made, stored and analyzed during theequalization period (for example, 40-100 individual pressuremeasurements). Among the time points sampled during the first 50 ms ofthe equalization period, there is a theoretically optimized samplingpoint for conducting the adiabatic calculations (e.g., see FIG. 43 inwhich the optimized sampling point occurs at about 50 ms after openingof the valve X2). The optimized sampling point may occur at a time earlyenough after valve X2 opening to minimize thermal transfer between thegas volumes of the two chambers, but not so early as to introducesignificant errors in pressure measurements due to the properties of thepressure sensors and delays in valve actuation. However, as can be seenin FIG. 43, the pressures for the pump chamber and reference chambersmay be substantially unequal to each other at this point, and thusequalization may not be complete. (Note that in some cases, it may betechnically difficult to take reliable pressure measurements immediatelyafter the opening of valve X2, for example, because of the inherentinaccuracies of the pressure sensors, the time required for valve X2 tofully open, and the rapid initial change in the pressure of either thecontrol chamber or the reference chamber immediately after the openingof valve X2.)

During pressure equalization, when the final pressure for the controlchamber and reference chambers are not the same, Equation 2 becomes:

_PriVri ^(γ) +PdiVdi ^(γ)=Constant=PrfVrf ^(γ) +PdfVd ^(γ)  (8)

where: Pri=pressure in the reference chamber prior to opening valve X2,Pdi=pressure in the control chamber prior to opening valve X2, Prf=finalreference chamber pressure, Pdf=final control chamber pressure.

An optimization algorithm can be used to select a point in time duringthe pressure equalization period at which the difference between theabsolute values of ΔVd and ΔVr is minimized (or below a desiredthreshold) over the equalization period. (In an adiabatic process, thisdifference should ideally be zero, as indicated by Equation 5. In FIG.43 the point in time at which the difference between the absolute valuesof ΔVd and ΔVr is minimized occurs at the 50 ms line, marked “time atwhich final pressures identified.”) First, pressure data can becollected from the control and reference chambers at multiple points j=1through n between the opening of valve X2 and final pressureequalization. Since Vri, the fixed volume of the reference chambersystem before pressure equalization, is known, a subsequent value forVrj (reference chamber system volume at sampling point j after valve X2has opened) can be calculated using Equation 3 at each sampling pointPrj along the equalization curve. For each such value of Vrj, a valuefor ΔVd can be calculated using Equations 5 and 7, each value of Vrjthus yielding Vdij, a putative value for Vdi, the volume of the controlchamber system prior to pressure equalization. Using each value of Vrjand its corresponding value of Vdij, and using Equations 3 and 4, thedifference in the absolute values of ΔVd and ΔVr can be calculated ateach pressure measurement point along the equalization curve. The sum ofthese differences squared provides a measure of the error in thecalculated value of Vdi during pressure equalization for each value ofVrj and its corresponding Vdij. Denoting the reference chamber pressurethat yields the least sum of the squared differences of |ΔVd| and |ΔVr|as Prf, and its associated reference chamber volume as Vrf, the datapoints Prf and Pdf corresponding to Vrf can then be used to calculate anoptimized estimate of Vdi, the initial volume of the control chambersystem.

One method for determining where on the equalization curve to capture anoptimized value for Pdf and Prf is as follows:

-   -   1) Acquire a series of pressure data sets from the control and        reference chambers starting just before the opening of valve X2        and ending with Pr and Pd becoming close to equal. If Pri is the        first reference chamber pressure captured, then the subsequent        sampling points in FIG. 32 will be referred to as Prj=Pr1, Pr2,        . . . Prn.    -   2) Using Equation 6, for each Prj after Pri, calculate the        corresponding ΔVrj where j represents the jth pressure data        point after Pri.

ΔVrj=Vrj−Vri=Vri(−1+(Prj/Pri)^(−(1/γ)))

-   -   3) For each such ΔVrj calculate the corresponding Vdij using        Equation 7. For example:

Δ Vr 1 = Vri * (−1 + (Pr  1/Pri)^(−(1/γ)))Δ Vd 1 = −Δ Vr 1Therefore, Vdi 1 = Δ Vd 1/(−1 + (Pd 1/Pdi)^(−(1/γ)))⋮ Vdin = Δ Vdn/(−1 + (Pdn/Pdi)^(−(1/γ)))

Having calculated a set of n control chamber system initial volumes(Vdi1 to Vdin) based on the set of reference chamber pressure datapoints Pr1 to Prn during pressure equalization, it is now possible toselect the point in time (f) that yields an optimized measure of thecontrol chamber system initial volume (Vdi) over the entire pressureequalization period.

-   -   4) Using Equation 7, for each Vdi1 through Vdin, calculate all        ΔVdj,k using control chamber pressure measurements Pd for time        points k=1 to n.

For the Vdi corresponding to Pr1:

Δ Vd 1, 1 = Vdi 1 * (−1 + (Pd 1/Pdi)^(−1(1/γ)))Δ Vd 1, 2 = Vdi 1 * (−1 + (Pd 2/Pdi)^(−1(1/γ)))⋮Δ Vd 1, n = Vd 1 * (−1 + Pdn/Pdi)^(−(1/γ)))⋮ For  the  Vdi  corresponding  to  Prn  :Δ Vdn, 1 = Vdin * (−1 + (Pd 1/Pdi)^(−(1/γ)))Δ Vdn, 2 = Vdin * (−1 + (Pd 2/Pdi)^(−(1/γ))) ⋮Δ Vdn, n = Vdin * (−1 + (Pdn/Pdi)^((1/γ)))

-   -   5) Take the sum-square error between the absolute values of the        ΔVr's and ΔVdj,k's

$S_{1}{\sum\limits_{k = 1}^{n}\left( {{{\Delta \; V_{{d\; 1},k}}} - {{\Delta \; V_{rk}}}} \right)^{2}}$

-   -   -   [S1 represents the sum-square error of |ΔVd| minus |ΔVr|            over all data points during the equalization period when            using the first data point Pr1 to determine Vdi, the control            chamber system initial volume, from Vr1 and ΔVr.]

$S_{2}{\sum\limits_{k = 1}^{n}\left( {{{\Delta \; V_{{d\; 2},k}}} - {{\Delta \; V_{rk}}}} \right)^{2}}$

-   -   -   [S2 represents the sum-square error of |ΔVr| minus |ΔVd|            over all data points during the equalization period when            using the second data point Pr2 to determine Vdi, the            control chamber system initial volume, from Vr2 and ΔVr.]

⋮$S_{n}{\sum\limits_{k = 1}^{n}\left( {{{\Delta \; V_{{d\; n},k}}} - {{\Delta \; V_{rk}}}} \right)^{2}}$

-   -   6) The Pr data point between Pr1 and Prn that generates the        minimum sum-square error S from step 5 (or a value that is below        a desired threshold) then becomes the chosen Prf, from which Pdf        and an optimized estimate of Vdi, the control chamber initial        volume, can then be determined. In this example, Pdf occurs at,        or about, the same time as Prf.    -   7) The above procedure can be applied any time that an estimate        of the control chamber volume is desired, but can preferably be        applied at the end of each fill stroke and each delivery stroke.        The difference between the optimized Vdi at the end of a fill        stroke and the optimized Vdi at the end of a corresponding        delivery stroke can be used to estimate the volume of liquid        delivered by the pump.

Air Detection

Another aspect of the invention involves the determination of a presenceof air in the pump chamber 181, and if present, a volume of air present.Such a determination can be important, e.g., to help ensure that apriming sequence is adequately performed to remove air from the cassette24 and/or to help ensure that air is not delivered to the patient. Incertain embodiments, for example, when delivering fluid to the patientthrough the lower opening 187 at the bottom of the pump chamber 181, airor other gas that is trapped in the pump chamber may tend to remain inthe pump chamber 181 and will be inhibited from being pumped to thepatient unless the volume of the gas is larger than the volume of theeffective dead space of pump chamber 181. As discussed below, the volumeof the air or other gas contained in pump chambers 181 can be determinedin accordance with aspects of the present invention and the gas can bepurged from pump chamber 181 before the volume of the gas is larger thanthe volume of the effective dead space of pump chamber 181.

A determination of an amount of air in the pump chamber 181 may be madeat the end of a fill stroke, and thus, may be performed withoutinterrupting a pumping process. For example, at the end of a fill strokeduring which the membrane 15 and the pump control region 1482 are drawnaway from the cassette 24 such that the membrane 15/region 1482 arebrought into contact with the wall of the control chamber 171, the valveX2 may be closed, and the reference chamber vented to atmosphericpressure, e.g., by opening the valve X3. Thereafter, the valves X1 andX3 may be closed, fixing the imaginary “piston” at the valve X2. Thevalve X2 may then be opened, allowing the pressure in the controlchamber and the reference chamber to equalize, as was described abovewhen performing pressure measurements to determine a volume for thecontrol chamber.

If there is no air bubble in the pump chamber 181, the change in volumeof the reference chamber, i.e., due to the movement of the imaginary“piston,” determined using the known initial volume of the referencechamber system and the initial pressure in the reference chamber, willbe equal to the change in volume of the control chamber determined usingthe known initial volume of the control chamber system and the initialpressure in the control chamber. (The initial volume of the controlchamber may be known in conditions where the membrane 15/control region1482 are in contact with the wall of the control chamber or in contactwith the spacer elements 50 of the pump chamber 181.) However, if air ispresent in the pump chamber 181, the change in volume of the controlchamber will actually be distributed between the control chamber volumeand the air bubble(s) in the pump chamber 181. As a result, thecalculated change in volume for the control chamber using the knowninitial volume of the control chamber system will not be equal to thecalculated change in volume for the reference chamber, thus signalingthe presence of air in the pump chamber.

If there is air in the pump chamber 181, the initial volume of thecontrol chamber system Vdi is actually equal to the sum of the volume ofthe control chamber and lines L0 and L1 (referred to as Vdfix) plus theinitial volume of the air bubble in the pump chamber 181, (referred toas Vbi), as shown in Equation 9:

Vdi=Vbi+Vdfix  (9)

With the membrane 15/control region 1482 pressed against the wall of thecontrol chamber at the end of a fill stroke, the volume of any air spacein the control chamber, e.g., due to the presence of grooves or otherfeatures in the control chamber wall, and the volume of the lines L0 andL1—together Vdfix—can be known quite accurately. (Similarly, with themembrane 15/control region 1482 pressed against the spacer elements 50of the pump chamber 181, the volume of the control chamber and the linesL0 and L1 can be known accurately.) After a fill stroke, the volume ofthe control chamber system is tested using a positive control chamberpre-charge. Any discrepancy between this tested volume and the testedvolume at the end of the fill stroke may indicate a volume of airpresent in the pump chamber. Substituting from Equation 9 into Equation7, the change in volume of the control chamber ΔVd is given by:

ΔVd=(Vbi+Vdfix)(−1+(Pdf/Pdi)^(−(1/γ)))  (10)

Since ΔVr can be calculated from Equation 6, and we know from Equation 5that ΔVr=(−1) ΔVd, Equation 10 can be re-written as:

(−1)ΔVr=(Vbi+Vdfix)(−1+(Pdf/Pdi)^(−(1/γ)))  (11)

and again as:

Vbi=(−1)ΔVr/(−1+(Pdf/Pdi)^(−(1/γ)))−Vdfix  (12)

Accordingly, the cycler 14 can determine whether there is air in thepump chamber 181, and the approximate volume of the bubble usingEquation 12. This calculation of the air bubble volume may be performedif it is found, for example, that the absolute values of ΔVr (asdetermined from Equation 6) and ΔVd (as determined from Equation 7 usingVdi=Vdfix) are not equal to each other. That is, Vdi should be equal toVdfix if there is no air present in the pump chamber 181, and thus theabsolute value for ΔVd given by Equation 7 using Vdfix in place of Vdiwill be equal to ΔVr.

After a fill stroke has been completed, and if air is detected accordingto the methods described above, it may be difficult to determine whetherthe air is located on the pump chamber side or the control side of themembrane 15. Air bubbles could be present in the liquid being pumped, orthere could be residual air on the control (pneumatic) side of the pumpmembrane 15 because of a condition (such as, for example, an occlusion)during pumping that caused an incomplete pump stroke, and incompletefilling of the pump chamber. At this point, an adiabatic FMS measurementusing a negative pump chamber pre-charge can be done. If this FMS volumematches the FMS volume with the positive precharge, then the membrane isfree to move in both directions, which implies that the pump chamber isonly partially filled (possibly, for example, due to an occlusion). Ifthe value of the negative pump chamber pre-charge FMS volume equals thenominal control chamber air volume when the membrane 15/region 1482 isin contact with the inner wall of the control chamber, then it ispossible to conclude that there is an air bubble in the liquid on thepump chamber side of the flexible membrane.

Head Height Detection

In some circumstances, it may be useful to determine the heightwiselocation of the patient relative to the cassette 24 or other portion ofthe system. For example, dialysis patients in some circumstances cansense a “tugging” or other motion due to fluid flowing into or out ofthe patient's peritoneal cavity during a fill or drain operation. Toreduce this sensation, the cycler 14 may reduce the pressure applied tothe patient line 34 during fill and/or drain operations. However, tosuitably set the pressure for the patient line 34, the cycler 14 maydetermine the height of the patient relative to the cycler 14, theheater bag 22, drain or other portion of the system. For example, whenperforming a fill operation, if the patient's peritoneal cavity islocated 5 feet above the heater bag 22 or the cassette 24, the cycler 14may need to use a higher pressure in the patient line 34 to deliverdialysate than if the patient's peritoneal cavity is located 5 ft belowthe cycler 14. The pressure may be adjusted, for example, by alternatelyopening and closing a binary pneumatic source valve for variable timeintervals to achieve the desired target pump chamber pressure. Anaverage desired target pressure can be maintained, for example, byadjusting the time intervals to keep the valve open when the pumpchamber pressure is below the target pressure by a specified amount, andto keep the valve closed when the pump chamber pressure is above thetarget pressure by a specified amount. Any adjustments to maintain thedelivery of a complete stroke volume can be made by adjusting the filland/or delivery times of the pump chamber. If a variable orifice sourcevalve is used, the target pump chamber pressure can be reached byvarying the orifice of the source valve in addition to timing theintervals during which the valve is opened and closed. To adjust forpatient position, the cycler 14 may momentarily stop pumping of fluid,leaving the patient line 34 in open fluid communication with one or morepump chambers 181 in the cassette (e.g., by opening suitable valve portsin the cassette 24). However, other fluid lines may be closed, such asthe upper valve ports 192 for the pump chambers 181. In this condition,the pressure in the control chamber for one of the pumps may bemeasured. As is well known in the art, this pressure correlates with the“head” height of the patient, and can be used by the cycler 14 tocontrol the delivery pressure of fluid to the patient. A similarapproach can be used to determine the “head” height of the heater bag 22(which will generally be known), and/or the solution containers 20, asthe head height of these components may have an effect on pressureneeded for pumping fluid in a suitable way.

Noise Reduction Features of the Cycler

In accordance with aspects of the invention, the cycler 14 may includeone or more features to reduce noise generated by the cycler 14 duringoperation and/or when idle. In one aspect of the invention, the cycler14 may include a single pump that generates both pressure and vacuumthat are used to control the various pneumatic systems of the cycler 14.In one embodiment, the pump can simultaneously generate both pressureand vacuum, thereby reducing overall run time, and allowing the pump torun more slowly (and thus more quietly). In another embodiment, the airpump start and/or stop may be ramped, e.g., slowly increases pump speedor power output at starting and/or slowly decreases pump speed or poweroutput at shut down. This arrangement may help reduce “on/off” noiseassociated with start and stop of the air pump so pump noise is lessnoticeable. In another embodiment, the air pump may be operated at alower duty cycle when nearing a target output pressure or volume flowrate so that the air pump can continue operating as opposed to shuttingoff, only to be turned on after a short time. As a result, disruptioncaused by repeated on and off cycles of the air pump may be avoided.

FIG. 44 shows a perspective view of an interior section of the cycler 14with the upper portion of the housing 82 removed. In this illustrativeembodiment, the cycler 14 includes a single air pump 83, which includesthe actual pump and motor drive contained within a sound barrierenclosure. The sound barrier enclosure includes an outer shield, such asa metal or plastic frame, and a sound insulation material within theouter shield and at least partially surrounding the motor and pump. Thisair pump 83 may simultaneously provide air pressure and vacuum, e.g., toa pair of accumulator tanks 84. One of the tanks 84 may store positivepressure air, while the other stores vacuum. A suitable manifold andvalve arrangement may be coupled to the tanks 84 so as to provide andcontrol air pressure/vacuum supplied to the components of the cycler 14.

In accordance with another aspect of the invention, components thatrequire a relatively constant pressure or vacuum supply during cycleroperation, such as an occluder, may be isolated from the source of airpressure/vacuum at least for relatively long periods of time. Forexample, the occluder 147 in the cycler 14 generally requires a constantair pressure in the occluder bladder 166 so that the patient and drainlines remain open for flow. If the cycler 14 continues to operateproperly without power failure, etc., the bladder 166 may be inflatedonce at the beginning of system operation and remain inflated until shutdown. The inventors have recognized that in some circumstances airpowered devices that are relatively static, such as the bladder 166, may“creak” or otherwise make noise in response to slight variations insupplied air pressure. Such variations may cause the bladder 166 tochange size slightly, which causes associated mechanical parts to moveand potentially make noise. In accordance with an aspect of the bladder166 and other components having similar pneumatic power requirements,may be isolated from the air pump 83 and/or the tanks 84, e.g., by theclosing of a valve, so as to reduce variations of pressure in thebladder or other pneumatic component, thus reducing noise that may begenerated as a result of pressure variations. Another component that maybe isolated from the pneumatic supply is the bladder in the door 141 atthe cassette mounting location 145 which inflates to press the cassette24 against the control surface 148 when the door 141 is closed. Othersuitable components may be isolated as desired.

In accordance with another aspect of the invention, the speed and/orforce at which pneumatic components are actuated may be controlled to asto reduce noise generated by component operation. For example, movementof the valve control regions 1481 to move a corresponding portion of thecassette membrane 15 so as to open or close a valve port on the cassette24 may cause a “popping” noise as the membrane 15 slaps against and/orpull away from the cassette 24. Such noise may be reduced by controllingthe rate of operation of the valve control regions 1481, e.g., byrestricting the flow rate of air used to move the control regions 1481.Air flow may be restricted by, for example, providing a suitably smallsized orifice in the line leading to the associated control chamber, orin other ways.

A controller may also be programmed to apply pulse width modulation(“PWM”) to the activation of one or more pneumatic source valves at amanifold of cycler 14. The pneumatic pressure delivered to variousvalves and pumps of cassette 24 can be controlled by causing theassociated manifold source valves to open and close repeatedly duringthe period of actuation of a valve or pump in cassette 24. The rate ofrise or fall of pressure against membrane 15/control surface 148 canthen be controlled by modulating the duration of the “on” portion of theparticular manifold valve during the actuation period. An additionaladvantage of applying PWM to the manifold source valves is that variablepneumatic pressure can be delivered to the cassette 24 components usingonly a binary (on-off) source valve, rather than a more expensive andpotentially less reliable variable-orifice source valve.

In accordance with another aspect of the invention, the movement of oneor more valve elements may be suitably damped so as to reduce noisegenerated by valve cycling. For example, a fluid (such as a ferro fluid)may be provided with the valve element of high frequency solenoid valvesto damp the movement of the element and/or reduce noise generated bymovement of the valve element between open and closed positions.

In accordance with another embodiment, pneumatic control line vents maybe connected together and/or routed into a common, sound-insulated spaceso that noise associated with air pressure or vacuum release may bereduced. For example, when the occluder bladder 166 is vented to allowthe spring plates 165 to move toward each other and occlude one or morelines, the air pressure released may be released into a sound insulatedenclosure, as opposed to being released into a space where noiseassociated with the release may be heard more easily. In anotherembodiment, lines that are arranged to release air pressure may beconnected together with lines that are arranged to release an airvacuum. With this connection (which may include a vent to atmosphere, anaccumulator or other), noise generated by pressure/vacuum release may befurther reduced.

Control System

The control system 16 described in connection with FIG. 1 has a numberof functions, such as controlling dialysis therapy and communicatinginformation related to the dialysis therapy. While these functions maybe handled by a single computer or processor, it may be desirable to usedifferent computers for different functions so that the implementationsof those functions are kept physically and conceptually separate. Forexample, it may be desirable to use one computer to control the dialysismachinery and another computer to control the user interface.

FIG. 45 shows a block diagram illustrating an exemplary implementationof control system 16, wherein the control system comprises a computerthat controls the dialysis machinery (an “automation computer” 300) anda separate computer that controls the user interface (a “user interfacecomputer” 302). As will be described, safety-critical system functionsmay be run solely on the automation computer 300, such that the userinterface computer 302 is isolated from executing safety-criticalfunctions.

The automation computer 300 controls the hardware, such as the valves,heaters and pumps, that implement the dialysis therapy. In addition, theautomation computer 300 sequences the therapy and maintains a “model” ofthe user interface, as further described herein. As shown, theautomation computer 300 comprises a computer processing unit(CPU)/memory 304, a flash disk file system 306, a network interface 308,and a hardware interface 310. The hardware interface 310 is coupled tosensors/actuators 312. This coupling allows the automation computer 300to read the sensors and control the hardware actuators of the APD systemto monitor and perform therapy operations. The network interface 308provides an interface to couple the automation computer 300 to the userinterface computer 302.

The user interface computer 302 controls the components that enable dataexchange with the outside world, including the user and external devicesand entities. The user interface computer 302 comprises a computerprocessing unit (CPU)/memory 314, a flash disk file system 316, and anetwork interface 318, each of which may be the same as or similar totheir counterparts on the automation computer 300. The Linux operatingsystem may run on each of the automation computer 300 and the userinterface computer 302. An exemplary processor that may be suitable foruse as the CPU of the automation computer 300 and/or for use as the CPUof the user interface computer 302 is Freescale's Power PC 5200B®.

Via the network interface 318, the user interface computer 302 may beconnected to the automation computer 300. Both the automation computer300 and the user interface computer 302 may be included within the samechassis of the APD system. Alternatively, one or both computers or aportion of said computers (e.g., display 324) may be located outside ofthe chassis. The automation computer 300 and the user interface computer302 may be coupled by a wide area network, a local area network, a busstructure, a wireless connection, and/or some other data transfermedium.

The network interface 318 may also be used to couple the user interfacecomputer 302 to the Internet 320 and/or other networks. Such a networkconnection may be used, for example, to initiate connections to a clinicor clinician, upload therapy data to a remote database server, obtainnew prescriptions from a clinician, upgrade application software, obtainservice support, request supplies, and/or export data for maintenanceuse. According to one example, call center technicians may access alarmlogs and machine configuration information remotely over the Internet320 through the network interface 318. If desired, the user interfacecomputer 302 may be configured such that connections may only beinitiated by the user or otherwise locally by the system, and not byremote initiators.

The user interface computer 302 also comprises a graphics interface 322that is coupled to a user interface, such as the user interface 144described in connection with FIG. 10. According to one exemplaryimplementation, the user interface comprises a display 324 that includesa liquid crystal display (LCD) and is associated with a touch screen.For example, a touch screen may be overlaid on the LCD so that the usercan provide inputs to the user interface computer 302 by touching thedisplay with a finger, stylus or the like. The display may also beassociated with an audio system capable of playing, among other things,audio prompts and recorded speech. The user may adjust the brightness ofthe display 324 based on their environment and preference. Optionally,the APD system may include a light sensor, and the brightness of thedisplay may be adjusted automatically in response to the amount ofambient light detected by the light sensor. The brightness of thedisplay may be set by the users for two different conditions: highambient light and low ambient light. The light sensor will detect theambient light level and the control system 16 will set the displaybrightness to the preselected levels for either high or low ambientlight based on the measured ambient light. The user may select thebrightness level for high and low ambient light by selection a valuefrom 1 to 5 for each condition. The user interface may be a slider barfor each condition. In another example the user may select a number. Thecontrol system may set the button light levels to match the displaylight levels.

The LCD display and/or the touch screen of the display 324 may developfaults, where they do not display and/or respond correctly. One theory,but not the only theory, of the cause is an electro-static dischargefrom a user to the screen that changes the values in the memories of thedrivers for the LCD display and touch screen. The software processes UICexecutive 354 or the AC executive 354 may include a low prioritysub-process or thread that checks the constant memory registers of thedrivers for the touch screen and LCD display. If thread finds that anyof the constant values in the memory registers are different from thosestored elsewhere in the User Interface computer 302 or automationcomputer 300, then the thread calls for another software process toreinitialize the drivers for LCD display and/or the touch screen. In oneembodiment, the LCD display is driven by a Kieko Epson S1d13513 chip andthe touch screen is driven by Wolfson Microelectronics WM97156 chip.Examples of the constant register values include but are not limited tothe number of pixels display on the screen, the number colors displayed.

In addition, the user interface computer 302 comprises a USB interface326. A data storage device 328, such as a USB flash drive, may beselectively coupled to the user interface computer 302 via the USBinterface 326. The data storage device 328 may comprise a “patient datakey” used to store patient-specific data. Data from dialysis therapiesand/or survey questions (e.g., weight, blood pressure) may be logged tothe patient data key. In this way, patient data may be accessible to theuser interface computer 302 when coupled to the USB interface 326 andportable when removed from the interface. The patient data key may beused for transferring data from one system or cycler to another during acycler swap, transferring new therapy and cycler configuration data fromclinical software to the system, and transferring treatment history anddevice history information from the system to clinical software. Anexemplary patient data key 325 is shown in FIG. 65.

As shown, the patient data key 325 comprises a connector 327 and ahousing 329 coupled to the connector. The patient data key 325 may beoptionally be associated with a dedicated USB port 331. The port 331comprises a recess 333 (e.g., in the chassis of the APD system) and aconnector 335 disposed within the recess. The recess may be defined, atleast in part, by a housing 337 associated with the port 331. Thepatient data key connector 327 and the port connector 335 are adapted tobe selectively electrically and mechanically coupled to each other. Asmay be appreciated from FIG. 65, when the patient data key connector 327and the port connector 335 are coupled, the housing 329 of the patientdata storage device 325 is received at least partially within the recess333.

The housing 329 of the patient data key 325 may include visual cuesindicative of the port with which it is associated and/or be shaped toprevent incorrect insertion. For example, the recess 333 and/or housing337 of the port 331 may have a shape corresponding to the shape of thehousing 329 of the patient data key 325. For example, each may have anon-rectangular or otherwise irregular shape, such as an oblong shapewith an upper indentation as shown in FIG. 65. The recess 333 and/orhousing 337 of the port 331 and the housing 329 of the patient data key325 may include additional visual cues to indicate their association.For example, each may be formed of the same material and/or have thesame or a similar color and/or pattern.

In a further embodiment, as shown in FIG. 65A, the housing 329 of thepatient data key 325 may constructed to be sloped away from connector327 to carry any liquids that may splash onto the key 325 away fromconnector 327 and toward the opposite end of the housing 329, where ahole 339 in the housing 329 may help drain the liquid off and away fromthe patient data key 325 and its coupling with the port connector 335.

In one embodiment, the port 331 and recess 333 are located on the frontpanel 1084 of cycler 14 as shown in FIG. 9-11. The patient data key 325is inserted in the port 331 before the door 141 is closed and therapy isstarted. The door 141 includes a second recess 2802 to accommodate thepatient data key 325, when the door 141 is closed. Locating the patientdata key 325 behind the door 141 assures that all the therapy data maybe recorded on to the PDK. This location prevents a user from removingthe key mid-therapy.

Alternatively or additionally, the patient data key 325 may comprise averification code that is readable by the APD system to verify that thepatient data key is of an expected type and/or origin. Such averification code may be stored in a memory of the patient data key 325,and be read from the patient data key and processed by a processor ofthe APD system. Alternatively or additionally, such a verification codemay be included on an exterior of the patient data key 325, e.g., as abarcode or numeric code. In this case, the code may be read by a cameraand associated processor, a barcode scanner, or another code readingdevice.

If the patient data key is not inserted when the system is powered on,an alert may be generated requesting that the key be inserted. However,the system may be able to run without the patient data key as long as ithas been previously configured. Thus, a patient who has lost theirpatient data key may receive therapy until a replacement key can beobtained. Data may be stored directly to the patient data key ortransferred to the patient data key after storage on the user interfacecomputer 302. Data may also be transferred from the patient data key tothe user interface computer 302.

In addition, a USB Bluetooth® adapter 330 may be coupled to the userinterface computer 302 via the USB interface 326 to allow, for example,data to be exchanged with nearby Bluetooth®-enabled devices. Forexample, a Bluetooth®-enabled scale in the vicinity of the APD systemmay wirelessly transfer information concerning a patient's weight to thesystem via the USB interface 326 using the USB Bluetooth® adapter 330.Similarly, a Bluetooth®-enabled blood pressure cuff may wirelesslytransfer information concerning a patient's blood pressure to the systemusing the USB Bluetooth® adapter 330. The Bluetooth® adapter may bebuilt-in to the user interface computer 302 or may be external (e.g., aBluetooth® dongle).

The USB interface 326 may comprise several ports, and these ports mayhave different physical locations and be used for different USB device.For example, it may be desirable to make the USB port for the patientdata key accessible from the front of the machine, while another USBport may be provided at and accessible from the back of the machine. AUSB port for the Bluetooth® connection may be included on the outside ofthe chassis, or instead be located internal to the machine or inside thebattery door, for example.

As noted above, functions that could have safety-critical implicationsmay be isolated on the automation computer. Safety-critical informationrelates to operations of the APD system. For example, safety-criticalinformation may comprise a state of a APD procedure and/or thealgorithms for implementing or monitoring therapies. Non safety-criticalinformation may comprise information that relates to the visualpresentation of the screen display that is not material to theoperations of the APD system.

By isolating functions that could have safety-critical implications onthe automation computer 300, the user interface computer 302 may berelieved of handling safety-critical operations. Thus, problems with orchanges to the software that executes on the user interface computer 302will not affect the delivery of therapy to the patient. Consider theexample of graphical libraries (e.g., Trolltech's Qt® toolkit), whichmay be used by the user interface computer 302 to reduce the amount oftime needed to develop the user interface view. Because these librariesare handled by a process and processor separate from those of theautomation computer 300, the automation computer is protected from anypotential flaws in the libraries that might affect the rest of thesystem (including safety-critical functions) were they handled by thesame processor or process.

Of course, while the user interface computer 302 is responsible for thepresentation of the interface to the user, data may also be input by theuser using the user interface computer 302, e.g., via the display 324.To maintain the isolation between the functions of the automationcomputer 300 and the user interface computer 302, data received via thedisplay 324 may be sent to the automation computer for interpretationand returned to the user interface computer for display.

Although FIG. 45 shows two separate computers, separation of the storageand/or execution of safety-critical functions from the storage and/orexecution of non safety-critical functions may be provided by having asingle computer including separate processors, such as CPU/memorycomponents 304 and 314. Thus, it should be appreciated that providingseparate processors or “computers” is not necessary. Further, a singleprocessor may alternatively be used to perform the functions describedabove. In this case, it may be desirable to functionally isolate theexecution and/or storage of the software components that control thedialysis machinery from those that control the user interface, althoughthe invention is not limited in this respect.

Other aspects of the system architecture may also be designed to addresssafety concerns. For example, the automation computer 300 and userinterface computer 302 may include a “safe line” that can be enabled ordisabled by the CPU on each computer. The safe line may be coupled to avoltage supply that generates a voltage (e.g., 12 V) sufficient toenable at least some of the sensors/actuators 312 of the APD system.When both the CPU of the automation computer 300 and the CPU of the userinterface computer 302 send an enable signal to the safe line, thevoltage generated by the voltage supply may be transmitted to thesensors/actuators to activate and disable certain components. Thevoltage may, for example, activate the pneumatic valves and pump,disable the occluder, and activate the heater. When either CPU stopssending the enable signal to the safe line, the voltage pathway may beinterrupted (e.g., by a mechanical relay) to deactivate the pneumaticvalves and pump, enable the occluder, and deactivate the heater. In thisway, when either the automation computer 300 or the user interfacecomputer 302 deems it necessary, the patient may be rapidly isolatedfrom the fluid path, and other activities such as heating and pumpingmay be stopped. Each CPU can disable the safe line at any time, such aswhen a safety-critical error is detected or a software watchdog detectsan error. The system may be configured such that, once disabled, thesafe line may not be re-enabled until both the automation computer 300and user interface computer 302 have completed self-tests.

FIG. 46 shows a block diagram of the software subsystems of the userinterface computer 302 and the automation computer 300. In this example,a “subsystem” is a collection of software, and perhaps hardware,assigned to a specific set of related system functionality. A “process”may be an independent executable which runs in its own virtual addressspace, and which passes data to other processes using inter-processcommunication facilities.

The executive subsystem 332 includes the software and scripts used toinventory, verify, start and monitor the execution of the softwarerunning on the CPU of the automation computer 300 and the CPU of theuser interface computer 302. A custom executive process is run on eachof the foregoing CPUs. Each executive process loads and monitors thesoftware on its own processor and monitors the executive on the otherprocessor.

The user interface (UI) subsystem 334, handles system interactions withthe user and the clinic. The UI subsystem 334 is implemented accordingto a “model-view-controller” design pattern, separating the display ofthe data (“view”) from the data itself (“model”). In particular, systemstate and data modification functions (“model”) and cycler controlfunctions (“controller”) are handled by the UI model and cyclercontroller 336 on the automation computer 300, while the “view” portionof the subsystem is handled by the UI screen view 338 on the UI computer302. Data display and export functionality, such as log viewing orremote access, may be handled entirely by the UI screen view 338. The UIscreen view 338 monitors and controls additional applications, such asthose that provide log viewing and a clinician interface. Theseapplications are spawned in a window controlled by the UI screen view338 so that control can be returned to the UI screen view 338 in thecase of an alert, an alarm or an error.

The therapy subsystem 340 directs and times the delivery of the dialysistreatment. It may also be responsible verifying a prescription,calculating the number and duration of therapy cycles based upon theprescription, time and available fluids, controlling the therapy cycles,tracking fluid in the supply bags, tracking fluid in the heater bag,tracking the amount of fluid in the patient, tracking the amount ofultra-filtrate removed from patient, and detecting alert or alarmconditions.

The machine control subsystem 342 controls the machinery used toimplement the dialysis therapy, orchestrating the high level pumping andcontrol functionality when called upon by the therapy subsystem 340. Inparticular, the following control functions may be performed by themachine control subsystem 342: air compressor control; heater control;fluid delivery control (pumping); and fluid volume measurement. Themachine control subsystem 342 also signals the reading of sensors by theI/O subsystem 344, described below.

The I/O subsystem 344 on the automation computer 300 controls access tothe sensors and actuators used to control the therapy. In thisimplementation, the I/O subsystem 344 is the only application processwith direct access to the hardware. Thus, the I/O subsystem 344publishes an interface to allow other processes to obtain the state ofthe hardware inputs and set the state of the hardware outputs.

FPGA

In some embodiments, the Hardware Interface 310 in FIG. 45 may be aseparate processor from the automation computer 300 and the UserInterface 302 that may perform a defined set of machine controlfunctions and provide an additional layer of safety to the cyclercontroller 16. A second processor, such as a field programmable gatearray (FPGA) may increase the responsiveness and speed of the cycler 14by moving some computing tasks from the automation computer 300 to thehardware interface 310 (e.g., an FPGA), so that the automation computer300 can devote more resources to fluid management and therapy control,as these comprise resource-intensive calculations. The hardwareinterface 310 may control the pneumatic valves and record andtemporarily store data from the various sensors. The real time controlof the valves, pressure levels and data recording by the hardwareinterface 310 allows the automation computer 300 to send commands andreceive data, when the software processes or functions running on theautomation computer 300 are ready for them.

A hardware interface processor 310 may advantageously be implemented onany medical fluid delivery apparatus, including (but not limited to) aperitoneal dialysis cycler 14, in which fluid is pumped by one or morepumps and an arrangement of one or more valves from one or more sourcecontainers of fluid (e.g., dialysate solution bags, or a heater bagcontaining fluid to be infused) to a patient or user. It may also beimplemented on a fluid delivery apparatus that is configured to pumpfluid from a patient or user (e.g., peritoneal dialysis cycler) to areceptacle (e.g., drain bag). A main processor may be dedicated tocontrolling the proper sequence and timing of pumps and valves toperform specific functions (e.g., pumping from a solution bag to aheater bag, pumping from a heater bag to a user, or pumping from a userto a drain receptacle), and to monitor the volumes of fluid pumped fromone location to the next. A secondary (hardware interface) processor(e.g. an FPGA) may correspondingly be dedicated to collect and storedata received from various sensors (e.g., pressure sensors associatedwith the pumps, or temperature sensors associated with a heating system)at an uninterrupted fixed rate (e.g., about 100 Hz or 200 Hz), and tostore the data until it is requested by the main processor. It may alsocontrol the pumping pressures of the pumps at a rate or on a schedulethat is independent from any processes occurring in the main processor.In addition to other functions (see below) it may also open or closeindividual valves on command from the main processor.

In one example the Hardware Interface 310 may be a processor thatperforms a number of functions including but not limited to:

-   -   Acquiring pneumatic pressure sensor data on a predictable and        fine resolution time base;    -   Storing the pressure data with a timestamp until requested by        automation computer 300;    -   Validating the messages received from that automation computer        30;    -   Providing automated control of one or more pneumatic valves    -   Controlling some valves with a variable pulse width modulation        (PWM) duty cycle to provide Pick & Hold functionality and/or        control some valves with current feedback;    -   Provide automated and redundant safety checking of valve        combinations, maximum pressures and temperatures and ability.    -   Independent of the other computers 300, 302 putting the cycler        14 into a failsafe mode as needed.    -   Monitoring status of buttons on the cycler 14 and controlling        the level of button illumination;    -   Controlling the Auto Connect screw-drive mechanism 1321 and        monitoring the Auto-Connect position sensing;    -   Detecting the presence of solution caps 31 and/or spike caps 63;    -   Control of the pneumatic pump;    -   Control of the prime sensor LED and detector;    -   Detecting over-voltages and testing hardware to detect        over-voltages;    -   Controlling and monitoring one or more fluid detectors;    -   Monitoring the latch 1080 and proximity sensor 1076 on the door        141;    -   Monitoring critical voltages at the system level.

The Hardware Interface 310 may comprise a processor separate from theprocessors in the automation computer 300 and user interface 302, A to Dconverts and one or more IO boards. In another embodiment, the hardwareinterface is comprised of a FPGA (Field Programmable Gate Array). In oneembodiment the FPGA is a SPARTAN® 3A in the 400K gate and 256 ballpackage made by Xilinx Inc. of California. The Hardware Interface 310 isan intelligent entity that is employed to operate as an independentsafety monitor for many of the Control CPU functions. There are severalsafety critical operations where either the Hardware Interface or theControl CPU serves as a primary controller and the other serves as amonitor.

The hardware interface 310 serves to monitor the following automationcomputer 300 functions including but not limited to:

-   -   Monitoring the integrity of system control data being received        from the automation computer 300;    -   Evaluating the commanded valve configurations for combination        that could create a patient hazard during therapy;    -   Monitoring the fluid and pan temperature for excessive high or        low temperatures;    -   Monitoring and testing the overvoltage monitor; and    -   Provide a means for the automation computer 300 to validate        critical data returned from the hardware interface.

FIG. 45A is a schematic representation of one arrangement of theautomation computer 300, the UI computer 302 and the hardware interfaceprocessor 310. The hardware interface 310 is connected via acommunication line to the automation computer 300 and connects to thesensors and actuators 312 in the cycler 14. A voltage supply 2500provides power for the safety critical actuators that can be enabled ordisabled by any of the computers 300, 302, 310. The safety criticalactuators include but are not limited to the pneumatic valves, thepneumatic pump and a safety relay on the heater circuit. The pneumaticsystem is configured to safe condition when unpowered. The pneumaticsafe condition may include occluding the lines 28,34 to the patient,isolating the control chambers 171 and/or closing all the valves 184,186, 190, 192, on the cassette 24. The safety relay 2030 in the heatercircuit 2212 is open, preventing electrical heating, when the relay isunpowered. Each computer 300, 302, 310 controls a separate electricalswitch 2510 that can each interrupt power to the valves, pump and safetyrelay. If any of the three computers detects a fault condition, it canput the cycler 14 in a failsafe condition by opening one of the threeswitches 2510. The electrical switches 2510 are controlled by the safetyexecutive process 352, 354 in the UI computer 302, and automationcomputer 300 respectively.

FIG. 45B is a schematic illustration of the connections between theHardware Interface 310, the various sensors, the pneumatic valves, thebag heater and the automation computer 300. The Hardware Interface 300controls each of the pneumatic valves 2660-2667 and the pneumatic pumpor compressor 2600 via pulse-width-modulated DC voltages. FIG. 45Bpresents an alternative embodiment of the safe line 2632 supplying powerto the pneumatic valves 2660-2667, pump 2600 and heater safety relay2030, in which a single switch 2510 is driven by an AND gate 2532connected to the three computers 300, 302, 310. The prime sensor iscontrolled and monitored by the Hardware Interface 310. The brightnessof the button LEDs is controlled by the Hardware Interface 310 via aPWM'd voltage.

The data signals from the buttons, pressure sensors, temperature sensorsand other elements listed in FIG. 45B are monitored by the HardwareInterface 310, and the data is stored in a buffer memory until calledfor by the automation computer 300. The digital inputs are connecteddirectly to the Hardware Interface 310. The analog signals frompressure, temperature, current sensors and others are connected toAnalog-to-Digital-Converter (ADC) boards that convert the analog signalsto digital values and may a scale and/or offset the digital values. Theoutputs of the ADCs are communicated over SPI buses to the HardwareInterface 310. The data is recorded and stored in the buffer at a fixedrate. Some of the data signals may be recorded at a relatively slowrate, including the pressure data on the pressure reservoirs and thefluid trap, temperatures, and current measurements. The low speed datamay be recorded at 100 Hz. The adiabatic FMS volume measurementalgorithm can be improved with high speed pressure data that is recordedat regular intervals. In a preferred embodiment, the pressure data fromthe sensors on the control volume 171 and the reference chamber 174 arerecorded at 2000 Hz. The data may be stored in random-access-memory(RAM) along with a time stamp. The rate of data collection maypreferably proceed independently of the automation computer 300 and ofprocesses or subroutines on the hardware interface. The data is reportedto the automation computer 300, when a process calls for that value.

The transfer of data between the hardware interface 310 to theautomation computer 300 may occur in a two step process where a datapacket transferred and stored in a buffer before being validated andthen accepted for use by the receiving computer. In one example, thesending computer transmits a first data packet, followed by a secondtransmission of the cyclic redundancy check (CRC) value for the firstdata packet. The receiving computer stores the first data packet in amemory buffer and calculates a new CRC value first data packet. Thereceiving computer then compares the newly calculated CRC value to theCRC value received and accepts the first data packet if the two CRCvalues match. The cyclic redundancy check (CRC) is an error-detectingcode commonly used in digital networks and storage devices to detectaccidental changes to raw data. Blocks of data entering these systemsget a short check value attached, based on the remainder of a polynomialdivision of their contents; on retrieval the calculation is repeated,and corrective action can be taken against presumed data corruption ifthe check values do not match. The data is not transferred between theautomation computer and hardware interface if CRC values do not match.If multiple consecutive data packets fail the CRC test, the receivingcomputer may signal an alarm and put the machine in a fail-safecondition by de-energizing the safe line 2632. In one example, the alarmcondition occurs on the third consecutive failed CRC check.

The automation computer 300 passes commands to open selected valves andset specified pressures in specified volumes to the hardware interface300. The hardware interface 310 in turn controls the valve position byproviding a PWM'd voltage to each valve. The hardware interface 310opens valves as requested with a pick-and-hold algorithm, where thevalve is initially actuated with a high voltage or current, and thenheld in place with a lower voltage or current. Pick-and-hold operationof valves may advantageously reduce the power draw and the level of heatdissipation inside the cycler 14.

The hardware interface 310 controls the pressure in the specified volumeby opening and closing the valves between the specified volume and theappropriate pressure reservoir based on the measured pressure in thespecified volume. The hardware interface 310 may also control thepressure in the pressure reservoirs by opening and closing the valvesbetween a pneumatic pump and one of the pressure reservoirs based on themeasured pressure in the reservoir. The specified volumes may includeeach of the control chambers 171, the reference volumes 174, the fluidtrap and the positive and negative reservoirs. The hardware interface310 may control the pressure in each of these specified volumes via anumber of control schemes, including but not limited to on-off control,or proportional control of the valve with a PWM signal. In one example,as described above, the hardware interface 310 implements an on-offcontroller, sometimes referred to as a bang-bang controller, which setsa first and second limit and closes the valve when the pressure exceedsthe upper second limit and opens the valve when the pressure is lessthan the first lower limit. In another example, the hardware interface310 may operate valves between the specified volume and both pressurereservoirs to achieve a desired pressure. In other examples theautomation computer 300 may specify one or more valves and command aspecific valve to control the pressure as measured by a specifiedsensor.

The hardware interface 310 controls the position and operation of theAuto-Connect carriage. The movement and positioning of the Auto-Connectcarriage 146 is controlled in real time by the hardware interface basedon the measured position of the carriage 146. The automation computer300 may command a particular function or position for the carriage. Thehardware interface 310 carries out the commanded function withoutburdening memory or processing of the automation computer 300. Thepositioning of the carriage 146 is controlled with a feedback loop froma position sensor. In addition, the FPGA detects the presence ofsolution caps 31 and/or spike caps 63 with sensing elements 1112 asdescribed above. Alternatively, the presence of the caps 31 and/or spikecaps 63 can be detected by a range of sensing technologies, includingbut not limited to vision systems, optical sensors that can be blockedby a solution cap and/or spike cap, or, for example, a micro-switch onthe stripper element 1491.

The hardware interface 310 may implement safety functions independentlyof the automation computer 300 or the user interface computer 302. Theindependent action of the hardware interface 310 to disable the safetyline 2632 and/or signal an alarm to the safety executives 352, 354further reduces the possibility of an unsafe condition occurring. Thehardware interface 310 may send an alarm and/or de-energize the safeline 2632 for defined valve combinations at any time. Shutting thecycler down based on disallowed valve positions protects the patient andpreserves the ability to complete the therapy (after a reset if needed).The hardware interface 310 may also alarm and de-energize the safe lineat unsafe conditions including excessive temperature on the heater panand/or bag button, excessive pressure in control chamber or reservoir.The hardware interface may alarm and de-energize the safe line whenwater is detected in the fluid trap.

Heater Control System

The control systems described above may be used to ensure that thesolution delivered to a patient is maintained within a pre-determinedrange of temperatures. During the therapy process, the cycler 14 fillsthe heater bag 22 with solution from the connected solution containers20, via a heater bag line 26. The heater bag 22 rests on the heater pan142 which may include electrical resistance heaters. The heater bag 22may be covered with an insulated cover 143. A heater controller mayfunction so as to control the thermal energy delivered to the heater pan142 in order to control the temperature of the solution to a desired setpoint prior to delivering the solution to the patient. The solutiontemperature should be within a safe range prior to being delivered tothe patient's abdominal cavity in order to avoid injuring or causingdiscomfort to the patient, or causing hypothermia or hyperthermia. Theheater controller may also limit the temperature of the heater pan totouch-safe temperatures. The heater controller is constructed to heatand maintain the solution within a range of acceptable temperatures in atimely manner in order to ensure the most effective therapy.

FIG. 49-1 is a schematic view of an exemplary embodiment of a solutionheater system 500. In this example, the solution heater system 500 islocated within the housing 82 of the cycler 14. The housing includes aninsulated lid 143 that may be affixed to the top of the housing 82. Thehousing 82 and the heater lid 143 may therefore define a region thatserves to house the components of the solution heater system 500. Thesolution heater system may include the following elements: housing 82,heater lid 143, heater pan 22, heater elements 508, heater pantemperature sensors 504, button temperature sensor 506, insulating ring507 and heater control electronics 50. The heater pan 142 is positionedinside the housing 82, and may accommodate a heater bag 22 whenpositioned on top of the heater tray 142. Preferably, the heater pan 142is inclined to place the inlet and/or outlet of the heater bag in adependent position, to help ensure that fluid in the bag is always incontact with the inlet/outlet regardless of the amount of fluid in thebag. In an embodiment, there can be up to six or more heater pantemperature sensors 504 (only one exemplary heater pan temperaturesensor 504 is shown in FIG. 49-1) positioned along the floor of theheater pan 142. Additionally, there may be a button temperature sensor506 positioned within the heater pan 142. The button sensor 506 ispositioned to make good thermal contact with the heater bag, while beingthermally isolated from the heater pan 142 by an insulating ring 507, inorder to provide an approximation of the temperature of the fluid ordialysate in the bag. In another embodiment, the button sensor 506 maycomprise a pair of thermistors mounted on an aluminum button. Thealuminum button is thermally isolated by an insulating ring made of, forexample, LEXAN® 3412R plastic or another low thermal conductivitymaterial. The button temperature sensor 506 may be located near the endof the tray where the fluid lines connect to the heater bag 22 in orderto better measure the temperature of the fluid within the heater bagwhen the heater bag is less than approximately one-third full. Thebutton sensor 506 may also be referred to as the fluid or dialysatetemperature sensor. There may also be a plurality of heater elements 508positioned under the heater pan 142, more toward the superior end of thepan, with the bag sensor located more toward the dependent portion ofthe pan, in order for the sensor to provide a more accurate reading ofthe fluid temperature within the bag, and to be relatively unaffected bythe heater elements 508. The thermal output of the heater elements 508may be controlled by the heater control electronics 505 to achieve thedesired fluid temperature in the heater bag. The heater controlelectronics 505 may include but not be limited to a heater controlmodule 509 that produces a Pulse Width Modulation (PWM) signal (PWMsignal 511, represented in FIG. 49-2). Electrical hardware in theinput-output (10) subsystem 344 connects electrical power to the heaterelements 508 based on the PWM signal 511, and hardware on the IOsubsystem 344 reads the output of heater pan temperature sensors 504 andbutton temperature sensor 506. The PWM signal 511 may control the powersupplied to each of the heater elements 508, and consequently thesolution heater system 500 may then heat the heater bag 22 to auser-settable comfort temperature, which may be controlled within apreferred safe temperature range. The solution heater system 500 mayalso limit the surface temperature of the heater pan 142 to asafe-to-touch temperature. The hardware components of the heater controlcircuitry 505 may be part of controller 16. There may also be insulation510 positioned below the heater element 508 which functions to thermallyisolate the heater pan 142 and heater bag 22 from the electronic andpneumatic components of the cycler 12. Additionally, the heater lid 143may insulate the heater bag 22 from the surrounding environment. Thesolution heater system 500 may thus be constructed to bring the solutiontemperature inside the heater bag 22, as measured by the buttontemperature sensor 506, to the desired fluid set point temperature 550(see FIG. 49-3) as quickly as possible, and maintaining that desiredfluid set point temperature 550 through the rest of the therapy cycle.In some embodiments, the temperature sensors connect to the hardwareinterface 310. The same hardware interface 310 may control a safetyrelay that disables the heater.

In some embodiments, the heater elements may include thermal switchesthat open when the temperature of the switch exceeds a firstpre-determined value. The switch will close again once the temperatureof the switch drops below the second lower pre-determined value. Thethermal switch may be incorporated directly into the heater elements ormay be mounted on the outside of the heater element or on the heaterpan. The thermal switches provide an additional layer of protectionagainst unsafe pan temperatures.

In another example, the thermal switch may be a thermal fuse with aone-time fusible link. A service call will be required to replace theblown thermal fuse, which may advantageously provide an opportunity toinspect and/or test cycler 14 before restarting therapy. FIG. 49-2 showsa schematic block diagram of the software context of the heater controlsubsystem. In an embodiment, the logic of the heater control circuitry505 may be implemented as a heater control module 509 in the machinecontrol subsystem 342 in the APD System software architecture. Theheater controller software may be implemented in the controller 16 (FIG.45) as described below. Additionally, the therapy subsystem 340 maysupply information to the machine control subsystem 342 such as theheater bag volume and the set point for the button temperature sensor506. The heater elements 508 may be enabled by the therapy subsystem340. The machine control subsystem 342 may also read temperature valuesfrom the I/O subsystem 344, which is located below the machine controlsubsystem 342. Furthermore, the heater controller 509 may output a PWMsignal 511 which may then control the power supplied to the heaterelements 508.

In an embodiment, the machine control subsystem 342 may be calledperiodically (e.g., approximately every 10 milliseconds) to service theI/O subsystem 344, update variables, and detect conditions. The machinecontrol subsystem 342 may also send updated signals to the heatercontrol module 509 periodically (e.g., approximately every 10 ms.). Theupdated signals may include the heater bag volume, heater pantemperatures 515, the button temperature 517, the set point temperature550 and the heater enable function. The heater control module mayaverage some or all of these signals continuously, but only calculateand update its output 511 at a lower frequency (e.g, every 2 seconds).

In another aspect, the solution heater system 500 may be able to controlthe solution temperature in the heater bag 22 within a given range of adesired fluid set point temperature 550 (see FIG. 49-2 and FIGS.49-7-49-9). Furthermore, the solution heater system 500 has beendesigned to function within pre-defined specifications under a varietyof different operating conditions, such as a relatively wide range ofambient temperatures (e.g., approximately 5° C. to approximately 37°C.), bag fill volumes (e.g., approximately 0 mL to approximately 3200mL), and solution container 20 temperatures (e.g., between approximately5° C. and approximately 37° C.). In addition, the solution heater system500 is capable of functioning within specifications even if the solutionin the heater bag 22 and the solution introduced during the replenishcycle may be at different temperatures. The solution heater system 500has also been designed to function within specifications with heatersupply voltages varying as much as +10% of nominal voltage.

The solution heater system 500 may be considered to be an asymmetricalsystem, in which the solution heater system 500 can increase thesolution temperature with the heater elements 508, but relies on naturalconvection to lower the solution temperature in the heater bag 22. Theheat loss may be further limited by the insulation 510 and the insulatedcover 143. One possible consequence is that in the event of atemperature overshoot, the APD system 10 may delay a patient fill whilethe heater bag slowly cools. A possible consequence of placing theheater elements on the heater pan 142 is that the heater pan 142 may beat a substantially higher temperature than that of the heater bag 22during the heating process. A simple feedback control on the heater bagtemperature as recorded by the button temperature sensor 506, may notturn the heater off soon enough to avoid the thermal energy at a highertemperature in the heater pan from causing the heater bag 22 toovershoot the desired set point temperature 550. Alternativelycontrolling the heaters 508 to achieve a heater pan temperature 504 thatwould not cause the heater bag temperature to overshoot may result in aslow heater system and thus delay therapy.

In order to minimize the time for the solution in the heater bag toachieve the set point temperature 550 without overshoot, the heatercontrol module may implement a control loop that varies the electricalpower of the heater elements 508 to achieve a desired fluid temperaturein the heater bag, in part by controlling the equilibrium temperature ofthe heater pan 142, the heater bag 22 and the fluid within the heaterbag 22. In one embodiment, a Proportional-Integral (PI) controllercontrols an equilibrium temperature 532 that is a function of thetemperatures of the heater bag 22 and the heater pan 142 and the volumeof solution in the heater bag. The equilibrium temperature may beunderstood to be the temperature that the solution in the heater bag 22and the heater pan 142 would reach if the heater were turned off and thetwo components allowed to reach equilibrium. The equilibrium temperaturemay also be understood as the weighted average of the target temperaturefor the heater pan 142 and the measured temperature of thesolution-filled heater bag, weighted by the thermal capacitance of each.The equilibrium temperature may also be calculated as the weightedaverage of the measured heater pan temperature and the solutiontemperature, in which the temperatures are weighted by their respectivethermal capacitances. In an embodiment, the weighted average temperatureof the heater pan and fluid in the heater bag may be calculated as thesum of the target heater pan temperature times the thermal capacitanceof the heater pan plus the fluid temperature times the thermalcapacitance of the fluid in the heater bag, where the sum is divided bythe sum of the thermal capacitance of the heater pan plus the thermalcapacitance of the fluid in the heater bag. The weighted averages of theheater pan and fluid may be alternatively weighted by the mass of theheater pan and fluid in the bag or the volume of the heater pan andfluid in the bag.

The control of the equilibrium temperature may be implemented using anumber of control schemes, such as, for example, single feedback loopsusing proportional, integral and or derivative controllers and nestedloops. One embodiment of a control scheme using cascaded nested controlloops is shown in FIG. 49-3. The outer loop controller 514 may controlthe heater bag temperature as measured by the button temperature sensor506 to the fluid set point temperature 550 by varying the heater pan setpoint temperature 527 supplied to the inner loop controller 512.Alternatively, the outer loop controller 514 may control the equilibriumtemperature of the heater bag 22, fluid and heater pan 142 to the fluidset point temperature 550 by varying the heater pan set pointtemperature 527. The temperature of the heater bag 22 and fluid may bemeasured by the button temperature sensor 506 and the heater pantemperature may be measured by one or more of the heater pan temperaturesensors 504. The outer loop controller may include one or more of thefollowing elements: proportional controller, integral controller,derivative controller, saturation limits, anti-windup logic andzero-order hold logic elements.

The inner loop controller 512 may control the heater pan temperature tothe heater pan set point temperature 527 by varying the thermal outputof the heater elements 508. The temperature of the pan may be measuredby one or more of the heater pan temperature sensors 504. The inner loopcontroller may include one or more of the following elements:proportional controller, integral controller, derivative controller,saturation limits, anti-windup logic and zero-order hold logic elements.

An exemplary implementation of the heater control module 509 utilizes aPI regulator cascade-coupled with a Proportional-Integral-Derivative(PID) controller. In the FIG. 49-3 embodiment, a PID inner loopcontroller 512 may control the temperature of the heater pan 142, and aPI outer loop controller 514 may control the equilibrium temperature ofthe heater bag, the fluid in the heater bag and the heater pan asmeasured by the heater pan temperature sensors 504 and buttontemperature sensor 506. The loop controller 514 differs from a standardPI regulator in that any overshoot of the desired fluid set point 550 bythe solution heater system 500 may be minimized by a logic controllableintegrator as described below. In an embodiment, the heater pantemperature signal 515 and the button temperature sensor (heater bag)signal 517 are low-pass filtered through a pair of control filters 519at a relatively high frame rate (e.g., a full 100 Hz frame rate), whilethe heater control module 509 may change the output of the heaters at alower rate (e.g., rate of ½ Hz).

FIG. 49-4 shows a schematic diagram of one embodiment of the inner loopcontroller 512 (heater pan controller). In this embodiment, the innerloop controller 512 uses a standard PID regulator including but notlimited to a differencing element 519 to produce a temperature error anda proportional gain element 522 to create an PWM signal 511. The innerloop controller 512 may further include a discrete-time integrator 516to reduce the offset error. The inner loop controller 512 may alsoinclude an anti-windup logic element 518 to minimize overshoot due atemperature error existing for a long period of time when the output ofthe inner loop controller 512 is saturated. The inner loop controller512 may further include a discrete derivative term 520 that acts on theheater pan actual temperature 515 to improve heater responsiveness. Theinner loop controller 512 may further include a saturation limit element521 that sets a maximum and/or minimum allowed heater command or PWMsignal 511. The inner loop controller 512 may further include zero-orderhold logic 523 to hold the PWM signal 511 constant between controllercalculations that occur approximately every 2 seconds.

FIG. 49-5 shows a schematic diagram of the outer loop controller 514(button temperature sensor controller). In this example, the outer loopcontroller 514 utilizes a modified PI-type regulator, which may includedifferencing elements 531, an integrator 534 and a proportional gainelement 526. The outer loop controller 514 may further include anintegrator switching logic 522 and corresponding switch 529, to allowthe integrator to be switched on or off by logic in the heater controlmodule 509. The outer loop controller 514 may further include a commandfeed forward 524 to improve the responsiveness of the outer loopcontroller 514. The outer loop controller 514 may further include aproportional feedback term 526 to act on a weighted combination of thebutton temperature sensor target temperature 517 and the heater pantarget temperature 527. The resulting measurement is an equilibriumtemperature 532 as described above. The outer loop controller 514 mayfurther include a saturation limit element 521 and/or a low pass filter542. The saturation limit element 521 in the outer loop sets a maximumallowed target pan temperature 527. The low pass filter 542 may bedesigned to filter out transient control signals at frequencies outsidethe bandwidth of the solution heater system 500.

The integral elements 534 in the outer loop controller 514 may be turnedon by a switch 529 when some or all of the following conditions arepresent: the rate of change of the button temperature 517 is below apre-determined threshold, the button temperature 517 is within apre-determined number of degrees of the fluid set point temperature 550,or the bag volume is greater than a pre-determined minimum and neitherof the controllers 512, 514 are saturated. An equilibrium temperaturefeedback loop may control the transient behavior of the solution heatersystem 500, and may be dominant when the surrounding ambient temperatureis in a normal to elevated range. The action of the integrator 516 mayonly be significant in colder environments, which may result in asubstantial temperature difference between the button sensor actualtemperature 517 and the heater pan actual temperature 515 atequilibrium. The feed-forward term 524 may pass the fluid set pointtemperature 550 through to the heater pan target temperature 527. Thisaction will start the heater pan target temperature 527 at the fluid setpoint temperature 550, instead of zero, which thereby improves thetransient response of the solution heater system 500.

The heater module 509 may also include a check that turns off the PWMsignal 511 if the heater pan actual temperature 515 crosses apre-determined threshold (this threshold may be set to be slightlyhigher than the maximum allowed heater pan target temperature 527). Thischeck may not be triggered under normal operation, but may be triggeredif the heater bag 22 is removed while the temperature of the heater pan142 is at a pre-determined maximum value.

The PI controller 514 may include a proportional term that acts on theequilibrium temperature 532. The equilibrium temperature is the heaterbag temperature measured by the button sensor 506 that would result ifthe heater 508 was turned off and the heater pan 142 and thesolution-filled heater bag 22 were allowed to come to equilibrium. Theequilibrium temperature can be better understood by referring to FIG.49-6, which shows a schematic block diagram of the heater pan 142 andheater bag 22 in a control volume analysis 546. The control volumeanalysis 546 depicts a model environment in which the equilibriumtemperature 532 may be determined. In this illustrative embodiment, thesolution heater system 500 may be modeled in as control volume 548,which may comprise at least two thermal masses: the heater pan 142 andthe heater bag 22. The boundary of the control volume 548 may be assumedto function as a perfect insulator, in which the only heat transfer isbetween the heater pan 142 and the heater bag 22. In this model, thermalenergy 549 may be added to the system via the heater elements 508, butthermal energy may not be removed from the heater pan 142 and heater bag22. In this model, as in the solution heater system 500, it is desirableto heat the heater pan 142 just enough that the heater bag 22 reachesits target temperature as the heater pan 142 and heater bag 22 come toequilibrium. Therefore, the equilibrium temperature 532 may becalculated as a function of the initial temperature of the heater bag 22and the initial temperature of the heater pan 142:

E=M _(p) c _(p) T _(p) +V _(b)ρ_(b) c _(b) T _(b)=(M _(p) c _(p) +V_(b)ρ_(b) c _(b))T _(e)

where M_(p), c_(p) are the mass and specific heat of the heater pan 142,V_(p), ρ_(b), c_(b) are the volume, density and specific heat of thesolution in the bag, T_(p) and T_(b) are the temperatures of the heaterpan 515 and the button 517 respectively. Solving for the equilibriumtemperature yields a linear combination of pan and button temperatures:

T _(e) =cT _(b)+(1−c)T _(p)

-   -   where

$C = {{\frac{V_{b}}{k + V_{b}}\mspace{14mu} {and}\mspace{14mu} k} = \frac{M_{p}C_{p}}{\rho_{b}C_{b}}}$

The constant c is an equilibrium constant, k is the thermal capacitanceratio of the heater pan over the solution. The subscript b denotes thesolution in the heater bag 22, while p denotes the heater pan 142.

In this model, allowing the heater module 509 to control the equilibriumtemperature 532 during the initial transient may allow for rapid heatingof the heater bag 22 while also reducing the heater pan actualtemperature 515 sufficiently early to prevent thermal overshoot. The cparameter may be determined empirically. The heater module 509 may set cto a value larger than the measured value to underestimate the totalenergy required to reach the desired set point 550, further limiting thethermal overshoot of the solution heater system 500.

FIG. 49-7 shows graphically the performance of solution heater system500 of the disclosed embodiment operating under normal conditions. Themeasured temperatures of the heater pan sensors 504, the buttontemperature sensor 506 and an additional temperature probe are plottedagainst time. The fluid temperature probe was part of the experimentalsetup up to verify the control scheme. The fluid probe temperature isshown as line 552. The button temperature is shown as line 517 and theheat pan temperatures are shown as line 515. Line 550 is the targettemperature for the button temperature sensor 506. At the start of thistrial, the heater bag is substantially empty, the heater is off andfluid is not moving, so that all the temperatures are at a nominalvalue. At a time T=1, the fluid at 25 C starts to flow into the heaterbag 22 bringing down the probe and button temperatures 552, 517, whilethe heater turns on and increases the heater pan temperature 515. Undernormal operation, proportional control of the equilibrium temperature532 may be sufficient to heat the solution within the heater bag 22 to atemperature close to the desired fluid set point temperature 550.Therefore, in FIG. 49-7, the solution heater system 500 functionseffectively, and the heater pan actual temperature 515, the buttonsensor actual temperature 517, and a probe temperature 552 all convergeto the fluid set point temperature 550 within approximately 50 minutes.

FIG. 49-8 shows graphically the performance of the solution heatersystem 500 operated in a high temperature environment in which theambient temperature is 35 C. As described above, the trial begins withthe heater bag being substantially empty. Once the fluid starts to flowand the heater turns on, the probe and button temperatures 552, 517decrease and the heater pan temperature 515 increases. In a hightemperature environment, the solution heater system 500 functions in amanner substantially similar to normal conditions. Thus, proportionalcontrol of the equilibrium temperature 532 may again be sufficient toheat the solution within the heater bag 22 to a temperature close to thedesired fluid set point temperature 550. In FIG. 49-7, the solutionheater system 500 functions effectively and within desiredspecifications, and the heater pan actual temperature 515, the buttonsensor actual temperature 517, and a probe temperature 552 all convergeto the desired set point temperature 550 within approximately 30minutes.

FIG. 49-9 shows graphically the performance of the solution heatersystem 500 operated in a cold environment where the ambient temperatureis 10 degrees C. and the source fluid is 5 degrees C. As describedabove, the trial begins with the heater bag being substantially empty.Once the fluid starts to flow and the heater turns on, the probe andbutton temperatures 552, 517 decrease and the heater pan temperature 515increases. In a cold environment, setting the desired fluid set pointtemperature 550 equal to the equilibrium temperature 532 may lead to asteady-state error in the temperature of the button sensor 506. The heatloss in cold environments may necessitate a large temperature differencebetween the heater pan 142 and the button sensor 506 during thermalequilibrium. Since the equilibrium temperature 532 is a weighted sum ofthe heater pan 142 and the button sensor 506, the temperature of thebutton sensor 506 may be below the fluid set point temperature 550 ifthe temperature of the heater pan 142 is above the desired fluid setpoint temperature 550 at equilibrium. This may occur even if theequilibrium temperature 532 is equal to the fluid set point temperature550. To compensate for this steady-state-error an integral term may beadded to outer PI controller 514 that acts on the temperature error ofthe button sensor 506. The integrator 538 may be turned on when one ormore of the following conditions are met: a first derivative of thetemperature of the button sensor 506 is low; the button sensor 506 isclose to the fluid set point temperature 550, the volume of the heaterbag 22 exceeds a minimum threshold; and neither inner PID loop 512 orouter PI controller 514 are saturated. In this illustrative embodiment,the switching of the integral term may minimize the effect of theintegrator 538 during normal operation and may also minimize theovershoot caused by integration during temperature transients.Therefore, in FIG. 49-9, the solution heater system 500 functionseffectively and within desired specifications, and the heater pan actualtemperature 515, the button sensor actual temperature 517, and a probetemperature 552 all converge to the fluid set point temperature 550within approximately 30 minutes.

In summary, the disclosed temperature controller can achieve goodthermal control of a two component system, in which the mass of thefirst component varies over time, and in which the second componentincludes a heater or cooler, and both components are in an insulatedvolume. This thermal control can be achieved by controlling theequilibrium temperature. The temperature controller determines thetemperature of both components as well as the mass of the variablecomponent. The temperature controller varies the heating or cooling ofthe second component to bring the equilibrium temperature to the desiredset point temperature. The equilibrium temperature is the thermalcapacitance weighted average temperature of the two components. Thecontroller may use a proportional feedback loop to control theequilibrium temperature.

The temperature controller may also include an integral term thatresponds to the difference between the set point temperature and thetemperature of the first component. The integral term may optionally beturned on when some or all of the following conditions are met:

-   -   the rate of temperature change of the first component is low;    -   the temperature of the first part is near the set point        temperature;    -   the volume of the first part exceeds some minimum level;    -   the control output signal is not saturated.

The temperature controller may also include a feed-forward term thatadds the set point temperature to the output of the proportional andintegral terms.

Further, the temperature controller may be the outer loop controller ofa cascade temperature controller in which the outer loop controllerincludes at least a proportional control term on the equilibriumtemperature and outputs a set point temperature for the innercontroller. The inner controller controls the temperature of the firstcomponent with the heater or cooler elements to the set pointtemperature produced by the outer controller.

Universal Power Supply

_In accordance with an aspect of the disclosure, the APD system 10 mayinclude a universal power supply that converts line voltage to one ormore levels of DC voltage for some or all of the electro-mechanicalelements and electronics in the cycler 14, and provides AC power to theelectric heater for the heater pan 142. The electro-mechanical elementsin the cycler 14 may include pneumatic valves, electric motors, andpneumatic pumps. The electronics in the cycler 14 may include thecontrol system 16, display 324, and sensors. AC power is supplied to aheater controller to control the temperature of the solution in theheater bag 22 on the heater tray 142 to a desired set point prior todelivering the solution to the user/patient. The universal power supplychanges the configuration of two (or more) heater elements toaccommodate two ranges of AC line voltages: e.g., a first range of110±10 volts rms; and a second range of 220±20 volts rms. Thisarrangement is intended to accommodate using the APD system 10 in anumber of different countries. During the start of a therapy session,the APD cycler 14 fills the heater bag 22 with solution from theconnected solution containers 20, via a heater bag line 26. In analternative embodiment, a pre-filled bag of solution may be placed on aheater pan 142 at the start of a therapy.

PWM Heater Circuit

The heater controller in the APD cycler modulates the electrical powerdelivered to the heater elements attached to the heater pan 142. The APDcycler may be used in various locations around the world and may beplugged into AC mains that supply power from 100 to 230 volts rms. Theheater controller and circuits may adapt to the variety of AC voltageswhile continuing to supply sufficient heater power and not blowing fusesor damaging heater elements in a number of ways.

One embodiment of a heater circuit is presented in FIG. 49-10, where apulse width modulator (PWM) based circuit 2005 controls the temperatureof the heater pan 142 with a pulse-width-modulated (PWM) element 2010connected between one lead of the AC mains 2040 and the heater element2000. The controller 2035 is operably connected to the relay 2030 andthe PWM element 2010. The controller 2035 monitors the operation of theheater by interrogating the voltage detect 2020 and temperature sensor2007. The controller 2035 may modulate the amount of power delivered tothe heater 2000 via a signal to the PWM element 2010. The PWM orpulse-width-modulated element is closed for some fraction of a fixedperiod between 0 and 100%. When the PWM element 2010 is closed 0% of thetime, no electrical energy flows to the heater 2000. The heater iscontinuously connected to the AC mains 2040 when the PWM element isclosed 100%. The controller 2035 can modulate the amount of powerdissipated by the heater 2000 by setting the PWM element 2010 to a rangeof values between 0 and 100%, inclusive.

The PWM elements 2010 switch large current flows on and off multipletimes a second. PWM elements 2010 are typically some kind of solid staterelay (SSR). SSRs for AC voltage typically include a triggering circuitthat controls the power switch. The triggering circuit may be, forexample, a reed relay, a transformer or an optical coupler. The powerswitch may be a silicon control rectifier (SCR) or a TRIAC. The SCR orTRIAC are also referred to as thyristors. One example of a SSR is theMCX240D5® by Crydom Inc.

In one example, the controller 2035 may modulate the PWM element valuein order to control the temperature of the heater pan 142 as measured bytemperature sensor 2007. In another example, the controller 2035 maymodulate the PWM element value to control the temperature of the fluidin the heater bag 22. In another example the controller 2935 may controlthe PWM element 2010 to provide a fixed schedule of heater power. Thecontroller 2035 may command a safety relay 2030 that opens the heatercircuit and stops the flow of electrical power to the heater 2000. Thesafety relay 2030 may be controlled by a separate controller (not shown)in order to provide a safety circuit independent of the controller 2035.

The PWM based circuit 2005 may include a voltage detect element 2020that provides a signal to the controller 2035 indicative of the voltageon the AC mains 2040. In one example, the voltage detect element 2020may measure the AC potential across the AC mains 2040. In anotherexample the voltage detect element 2020 may measure the current flowthrough the heater 2000. The controller 2035 may calculate the voltageacross the AC mains from a known resistance of the heater element 2000,the PWM element 2010 signal and the measured current.

The PWM based circuit 2005 may vary the maximum allowed duty cycle ofPWM element 2010 to accommodate different AC Mains voltage. The heaterelement 2000 may be designed to provide the maximum required power withthe lowest possible AC voltage. The controller may vary the duty cycleof the PWM element 2010 to provide a constant maximum heater power for arange of voltages at the AC mains. For example, the voltage supplied tothe heater 2000 from a 110 volt AC line may be supplied at a 100% dutycycle, and the same amount of electrical power may be delivered to theheater 2000 from a 220 volt AC line if the PWM element 2010 is set to25%. The duty cycle of the PWM element 2010 may be further reduced belowthe maximum value to control the temperature of the heater pan 142.

The temperature of the heater element 2000 and the heater pan 142 may becontrolled by the average heater power over a time constant that is afunction of the thermal mass of the element and heater pan. The averageheater power may be calculated from the heater resistance, which isrelatively constant, and the rms voltage across the heater element 2000.In a practical sized heater, the PWM frequency is much faster than thetime constant of the heater system, so the effective voltage across theheater element is simply the PWM duty cycle multiplied by the rmsvoltage.

One method to control the heater pan temperature of the circuit in FIG.49-10 may direct the controller 2035 to set a maximum PWM duty cyclebased on the measured voltage at 2020. The maximum duty cycle may becalculated from the desired maximum heater power, known resistance ofthe heater element 2000 and the measured voltage. One possible exampleof the calculation is:

PWM _(MAX)=(P _(MAX) *R _(HEATER))^(0.5) /V _(rms)

where PWM_(MAX) is the maximum allowed PWM duty cycle, P_(MAX) is themaximum heater power, R_(HEATER) is the nominal resistance of the heaterelement 2000, and V_(rms) is the supplied voltage as measured by theVoltage Detect 2020. Another example of the calculation is:

PWM _(MAX) =P _(MAX)(I ² *R _(HEATER))

where I is the current flow through heater when the voltage is applied.The controller 2035, after setting the maximum PWM duty cycle, thenvaries the PWM duty cycle of the PWM element 2010 to control thetemperature of the heater pan 142 as measured by a temperature sensor2007. The controller may control the PWM element to achieve a desiredtemperature in a number of ways, including, for example, a PID feedbackloop, or a PI feedback system.

In an alternative method and configuration, the PWM circuit 2005 doesnot include the voltage detect 2020. In this alternative method thecontroller 2035 varies the PWM duty cycle of the PWM element 2010 toachieve the desired heater pan temperature as measured by temperaturesensor 2007. The controller 2035 begins the heating cycle at a minimumPWM duty cycle and increases the PWM duty cycle until the temperaturesensor reports the desired temperature to the controller 2035. The rateof increase of the PWM rate may be limited or controlled to avoidexcessive currents that could trip and blow the fuses 2050. Thecontroller 2035 may alternatively use small gains in a feedbackcalculation to limit rate of PWM duty cycle increase. Alternatively thecontroller may use a feed forward control to limit the rate of PWM dutycycle increase.

Dual-Voltage Heater Circuit

An example of a dual-voltage heater circuit 2012 that changes theresistance of the heater is shown as a schematic block diagram in FIG.49-11. The block diagram in FIG. 49-11 presents one example of adual-voltage heater circuit 2012 to provide approximately constantheater power for the two standard AC voltages of 110 and 220 volts rms.Dual-voltage heater circuit 2012 limits the maximum current flow byreconfiguring the heater and thus is less sensitive to software errorssetting the duty cycle of the PWM element as in circuit 2005. Circuit2012 lowers the maximum current flows through the PWM element 2010 whichallows for smaller and less expensive SSRs. The selection of the heaterconfiguration in circuit 2012 is separated from the heater modulation toimprove control and reliability. The PWM elements 2010A, 2010B thatmodulate the heater power are typically SSR, which typically failclosed, thus providing maximum power. The heater select relay 2014 maybe an electromechanical relay, which while less than ideal for highcycle applications, may typically be preferred for safety criticalcircuits, due in part to the tendency of electromechanical relays tofail open. The selection of the heater configuration by the processorallows more control of heater configuration.

In the event of the AC Mains voltage fluctuating, perhaps due to abrown-out, the controller preferably holds the heater configurationconstant. In contrast, a circuit that automatically changes the heaterconfiguration based on the instantaneous voltage could fluctuate betweenheater configurations. This may result in high current flows if thecircuit does not respond fast enough to line voltage that returns to itsoriginal level from a temporarily lower level. In an embodiment, theprocessor receives input from the user or patient in selecting theheater configuration (parallel or series), and the dual-voltage heatercircuit 2012 does not automatically switch between configurations inresponse to fluctuating line voltage. In another embodiment, theprocessor measures the current flow in the series configuration (i.e.the higher resistance configuration) at full power, selects a heaterconfiguration appropriate to the AC mains voltage at the start oftherapy, and does not change configuration for the duration of therapy.

The dual-voltage heater circuit 2012 may comprise two heater elements2001, 2002 that can be connected in parallel or in series with oneanother to provide the same heater power for two different voltages atthe AC mains 2040. Each heater element 2001, 2002 may comprise one ormore heater sub-elements. The electrical resistance of heater elements2001, 2002 is preferably approximately equal. The controller 2035 mayreceive a signal from the current sense 2022 and control the heaterselect relay 2014 to connect the heater elements 2001, 2002 in eitherseries or parallel. The controller 2035 may change the electricalarrangement of the two heater elements to limit the current flowresulting from different AC mains voltages. One example of a currentsense 2022 is a current sense transformer AC-1005 made by Acme Electric.

The power in the heater elements 2001, 2002 may be further modulated bythe PWM elements 2010A, 2010B controlled by the controller 2035 toachieve a desired temperature as measured by temperature sensor 2007, orto achieve other control goals as described above. The PWM elements2010A, 2010B may be a solid state relays such as MCX240D5® by CrydomInc. The safety relay 2030 may be configured to disconnect the heaterelements 2001, 2002 from the AC mains 2040. The safety relay 2030 may becontrolled by the controller 2035 or another processor or safety circuit(not shown).

The safety relay 2030 and heater select relay 2014 may be solid state orelectro-mechanical relays. In a preferred embodiment, the safety relay2030 and/or heater select relay 2014 are electro-mechanical relays. Oneexample of an electro-mechanical relay is a G2AL-24-DC12 relay made byOMRON ELECTRONIC COMPONENTS and other manufacturers. Electro-mechanicalrelays are often preferred for safety critical circuits as they areconsidered to be more robust and more reliable than solid state relays,and have a tendency to fail open. They may also be less susceptible tovarious failures in the controller software.

In one example, the heater select relay 2014 comprises a double-poledouble-throw relay, in which the outputs connect to the heater elements2001, 2002. The heater select relay 2014, in the non-energized state,connects the heater elements 2001, 2002 in series such that the currentflows through one element and then the other. The series configurationmay be achieved, in one example circuit, by the following; connect thefirst end of the heater element 2001 to L1 circuit 2041 via PWM element2010A; connect the joined ends of heater elements 2001, 2002 to an opencircuit via the first pole 2014A; connect second end of heater element2002 to the L2 circuit 2042 via the second pole 2014B. In an energizedstate, the heater select relay 2014 connects the heater elements inparallel such that approximately half the current flows through each PWMand heater element. The parallel configuration may be achieved in thesame example circuit by the following: connect the first end of theheater element 2001 to L1 circuit 2041 via PWM element 2010A; connectthe second end of heater element 2002 to the L1 circuit 2041 via PWMelement 2010B; connect the joined ends of heater elements 2001, 2002 toL2 circuit 2042 via the first pole 2014A. The preferred circuit connectsthe heater elements 2001, 2002 in series in the unpowered condition asit is a safer configuration because the resulting higher resistance willlimit current flows and avoid overloading the fuses 2050, or overheatingthe heating elements 2001, 2002 if connected to a higher voltage ACmain.

Another example of a heater circuit 2112 that changes the effectiveresistance of the heater by changing the heater configuration is shownin FIG. 49-12 as a schematic block diagram. The heater circuit 2112 issimilar to heater circuit 2012 (shown in FIG. 49-11) except that heatercircuit 2112 provides better leakage current protection in the eventthat the L1 and L2 power circuits are reversed at the wall socket. Thereversal of the L1 and L2 power circuits is possible if the power wasincorrectly wired in the building that supplies power to the heatercircuit. Wiring in a residential building may not be as reliable as ahospital, where all the electrical system is installed and maintained byqualified personnel.

The electrical components and connections between the PWM elements2010A, 2010B, the nominal L1 circuit 2041, heater elements 2001, 2002,heater select relay 2014 and the nominal L2 circuit 2042 in heatercircuit 2112 are arranged to minimize leakage current regardless of wallsocket polarity. In the non-energized state as shown in FIG. 49-12, theheater select relay 2014 connects the heater elements 2001, 2002 inseries with the PWM element 2010A. One possible circuit that connectsthe heater elements in series includes: the first end of heater element2001 connected to the L1 circuit 2041 via PWM element 2010A; the secondend of heater element 2001 connected to the first end of heater element2002 via the first pole 2014A, a L1 2014C and the second pole 2014B; andthe second end of heater element 2002 connected to the L2 circuit 2042via PWM element 2010B. In the energized state, the heater elements 2001,2002 and PWM elements 2010A, 2010B are connected in parallel. In anenergized state, the heater select relay 2014 connects the heaterelements in circuit 2122 in parallel such that approximately half thecurrent flows through each PWM and heater element. One possible circuitto connect the two heater and PWM elements in parallel includes: thefirst end of heater element 2001 connected to the L1 circuit 2041 viaPWM element 2010A; the second end of heater element 2001 connected viathe first pole 2014A to the L2 circuit; the first end of heater element2002 is connected to the L1 circuit 2041 via the second pole 2014B; thesecond end of heater element 2002 is connected to the L2 circuit 2042via the PWM element 2010B. The safety relay 2030 is located on the L2circuit 2042 and creates a fail-safe condition of no current flow byopening if a fault occurs. The control of the safety relay is describedbelow. The controller 2035 controls the heater configuration to limitthe current flow as measured by the current sense 2022 to levels belowthe current rating for the fuses 2050, heater elements 20001, 2002, thePWM elements 2010A, 2010B and limits total heater power. The controller2035 varies the duty cycle of the PWM elements 2010A, 2010B to controlthe heater pan 142 temperature as measured by the sensor 2007.

Dual-Voltage Heater Circuit Implementation

A circuit diagram 2212 of one embodiment of the present invention isshown in FIG. 49-13, which is equivalent to heater circuit 2012 in FIG.49-11. In the circuit 2212, the heater elements 2001, 2002 are connectedin series by the heater select relay 2014 when the relay coil 2014D isnot energized. The controller (not shown) connects the heater elements2001, 2002 and PWM elements 2010A, 2010B in parallel by supplying asignal at node 2224, which closes transistor switch 2224A, andenergizing the relay coil using the Vs DC power 2214, The controllermodulates the heater power by varying the duty cycle of the PWM elements2010A, 2010B through a signal at node 2220 and powered with Vsupply2210. The current flow is measured with the current sense 2022. Thesafety relay 2030 is normally open. The safety relay 2030 may becontrolled by an FPGA board that is separate from the controller. TheFPGA board monitors the operation of the APD cycler, including theheater pan temperature and the current sense and several otherparameters. The FPGA board may open the relay by removing the signal atnode 2228. The safety relay coil 2030D is powered by the Vsafety 2218.

In one example, the voltage supplying Vsupply 2210, Vs 2214, Vsafety2218 may be the same voltage source. In another example each voltagesource be controllable to provide additional operation control of theheater circuit for added safety. In one example the Vsafety 2218 may becontrolled by multiple processors in the APD cycler 14. If any of theprocessors detects an error and fails, then the Vsafety circuit isopened, the Safety Relay 2030 is opened and heater power is turned off.

Dual-Voltage Heater Circuit Operation

The heater circuit is operated to provide adequate heater power withoutallowing damaging currents to flow through the heater elements 2001,2002 or the fuses 2050. The heater circuit 2212 may be configured beforethe therapies are run on the APD cycler 14 and not changed duringoperation regardless of the voltage changes in the AC mains. The controlsystem 16 (in FIG. 45) starts up the heater control circuit 2212 withthe heater select relay 2014 un-energized, so the heater elements areconnected in series to minimize the current. As one part of the startupprocesses, software in the automation computer 300 may run a currentflow test of the heaters by commanding the PWM elements 2010A, 2010B to100% duty cycle and the resulting test current is measured by thecurrent sense 2022 and communicated to the automation computer 300. Theduty cycle of the PWM elements 2010 may be reset to zero after currentflow test.

In one example method, the automation computer 300 evaluates themeasured test current against a predetermined value. If the measuredtest current is above a given value, the automation computer 300 willproceed with the ADP cycler startup procedure. If the measured testcurrent value is below that same given value, then the automationcomputer 300 will energize the heater select relay to reconfigure theheater elements 2001, 2002 in parallel. The current flow test isrepeated and if the new measured test current is above the predeterminedvalue the automation computer 300 will proceed with the ADP cyclerstartup procedure. If the measure test current from the current flowtest with parallel heater elements, is below above the predeterminedvalue, the automation computer 300 will signal an error to the userinterface computer 302.

Alternatively, the automation computer 300 may calculate a test voltagebased on the measured test current and heater element configuration. Ifthe test voltage is in the range of 180 to 250 volts rms, then theautomation computer 300 will proceed with the ADP cycler startupprocedure. If the test voltage is in the range of 90 to 130 V rms, thenthe automation computer 300 will energize the heater select relay toreconfigure the heater elements 2001, 2002 in parallel, repeat thecurrent flow test, and recalculate the test voltage. If the test voltageis in the range of 90 to 130 V rms, the automation computer 300 willproceed with the ADP cycler startup procedure, if not automationcomputer 300 will signal an error to the user interface computer 302.

In another example method, the automation computer 300 compares themeasured test current with the heater elements configured in series to aseries-low-range and series-high-range of current values. Theseries-low-range is consistent with a low AC voltage flowing through theheater elements arranged in series. The series-high-range is consistentwith a high AC voltage flowing through the heater elements arranged inseries. In an exemplary embodiment, the low AC voltage includes rmsvalues from 100 to 130 volts, while the high AC voltage includes rmsvalues from 200 to 250 volts.

If the measured test current is outside of low-range and the high-range,then the automation computer 300 may determine that the heater circuitis broken and signal an error to the user interface computer 302. If themeasured test current is within the high-range, the heater configurationis left unchanged and the startup of the APD cycler 14 may continue. Ifthe measured test current is within the low-range and the heaterelements are arranged in series, then the automation computer 300 mayreconfigure the heater elements 2001, 2002 to a parallel arrangement byenergizing the heater select relay 2014 through a signal at node 2224.The automation computer 300 may control the heater select relay 2014 viaa command sent to the hardware interface 310 that in turn provides thesignal to actuate the heater select relay 2014.

The automation computer 300 may repeat the current flow test afterreconfiguring the heater elements into a parallel arrangement by againcommanding the PWM elements 2010A, 2010B to 100% duty cycle andmeasuring the current flow with the current sense 2022. The measuredtest current may be evaluated against the parallel-low-range of currentvalues. If the measured test current is within the parallel-low-rangevalues proceed with the ADP cycler startup procedure. If the newlymeasured test current is outside the parallel-low-range values, thenautomation computer 300 will signal an error to the user interfacecomputer 302.

The FPGA controller implemented in the hardware interface 310 may beprogrammed to command the safety relay 2030 to open through a signal atnode 2228 while the heater select relay 2014 is switched. The safetyrelay 2030 may be opened each time the heater select relay 2014 isopened or closed to prevent a short circuit from one pole to the otherwithin the heater select relay 2014.

Dual-Voltage Heater Circuit Operation with User Input

In an alternative embodiment, the automation computer 300 may requireuser intervention before reconfiguring the heater elements 2001, 2002.Requiring user input provides a valuable safety feature of oneembodiment of the present invention. FIG. 49-14 shows a logic flow chartillustrating a method 2240 to include the user in configuring the heaterelements appropriately for the available AC voltage. In step 2241, thecontrol system 16 (in FIG. 45) starts up the heater control circuit 2212(FIG. 49-13) with the heater select relay 2014 un-energized, so theheater elements are connected in series to minimize the current. Insetup 2242, the automation computer 300 commands the PWM elements 2010A,2010B to 100% duty cycle and the current is measured by the currentsense 2022 and the measure test current is communicated to theprocessor. The duty cycle of the PWM elements 2010 may be reset to zeroafter the test current is measured. In step 2244, the automationcomputer 300 compares the measured test current to a first range. Instep 2245, if the measured test current is within the first range, thenthe heater configuration is correct and the APD operation proceeds instep 2254. In an alternative embodiment, method 2240 includes step 2245Awhere the user interface computer 302 ask the user to confirm the ACmains voltage that the automation computer 300 determined from measuredtest current and the heater configuration before proceeding from step2245. If the user does not confirm the AC voltage level, method 2240will proceed to step 2252 and displays an error.

In step 2246, if the measured current is outside the second range, thenmethod 2240 displays an error in step 2252, otherwise the method 2240proceeds to step 2247. In step 2247, if the user confirms low AC voltagethen the heater configuration will be changed in step 2248, otherwisethe method 2240 displays an error in step 2252. In step 2248, theautomation computer 300 reconfigures the heater elements 2001, 2002 to aparallel arrangement by energizing the heater select relay 2014 througha signal at node 2224. After reconfiguring the heater elements in step2248, the method 2240 retests the heater in step 2242 and continuesthrough the logic flow chart of method 2240.

An alternative embodiment, a user or patient may store the AC voltage ashigh or low in the memory of the control system 16 so that theautomation computer 300 need not query the user or patient at eachtreatment to confirm the AC voltage. FIG. 49-15 shows a logic flow chartillustrating a method 2260 where the AC voltage value is stored in thememory of the control system 16. The steps 2241 through 2246 are thesame as method 2240 described above. In step 2249, the memory is queriedfor the stored AC voltage value. If the stored AC voltage value is low,then the method 2260 proceeds to step 2248 and reconfigures the heaterelements into a parallel arrangement. If the stored AC voltage is highnor zero, then the user interface computer 302 may query the user toconfirm a low AC mains voltage. If a user confirms the low AC voltage,then the method 2260 proceeds to step 2248 and reconfigures the heaterelements into a parallel arrangement. Step 2248 may also include thesetting the stored AC voltage to low. After reconfiguring the heaterelements in step 2248, the method 2260 retests the heater in step 2242and continues through the logic flow chart of method 2260.

In one example, method 2260 may include a step 2245A which reads frommemory or calculates the test voltage from the measured test current andheater configuration and then has the user interface computer 302 asksthe user to confirm the test voltage. The method may include a stepbetween 2245 and 2246, where if the heater has been reconfigured to aparallel arrangement and the current is not within the high range, thenthe method proceeds to step 2252 and shuts down the APD cycler 14.

The methods 2240 and 2260 may evaluate the measured test current by anumber of different methods. A preferred method was described above andalternative examples are es are described below. The first range in step2245 may be a range of current levels that would provide the desiredamount of maximum heater power for the current heater elementconfiguration. Alternatively step 2245 may calculate a test voltage fromthe measured test current and heater element configuration and evaluateif the test voltage is correct for the heater configuration:approximately 110 V rms for parallel configuration and approximately 220V rms for series configuration. Alternatively step 2245 may test if themeasured test current is above a given predetermined value. The secondrange in step 2246 may be a range of current values corresponding toapproximately 110 V rms in a series configuration. Alternatively step2246 may calculate a test voltage from the measured test current andheater element configuration and evaluate if the test voltageapproximately 110 V rms for a series configuration. Alternatively, step2246 may evaluate if the measure test current is below a givenpredetermined value.

In another embodiment, the selected AC voltage value in method 2260 maybe preloaded in the factory or distribution center based on the expectedlocation of usage. For example, the AC voltage value may be selected forlow if the APD cycler will be used in the US, Canada or Japan. Foranother example, the AC voltage value may be selected for high if theAPD cycler will be used in Europe, or Asia.

For machines expected to operate in a given region, this database may beas simple as a regional voltage being loaded on the machine at thefactory, or loaded by a technician during initial set-up at a place ofoperation. These regional AC voltage value prescriptions may be enteredmanually, using a memory stick or similar device, using a personal datakey (PDK), a compact disc, bar code reader over the world wide web usingan Ethernet or wireless connection or by any other data transfermechanism obvious to one skilled in the art. In other embodiments, setsof regional voltages may be accessible to control system 16 and may beused to inform a user of the typical operating voltage in his or herarea. In one embodiment, prior to accepting a user input in step 2247 tochange voltage from a previous setting, a user would be informed of thetypical voltage of a region; thus a user unfamiliar with the value ofregional voltages would only be required to know his or her currentlocation to provide a safeguard against voltage incompatibility.

In another embodiment, APD cycler 14 would be equipped with a mechanismto determine its current location, for example a GPS tracker, anEthernet connection and a mechanism to determine the location of theconnection, or a mode where user interface 302 can be used to enter thepresent location, such as country or continent. In an embodiment, afterstarting up in a series heater configuration and running a current flowtest, a user may simply be queried as to his or her present location; ifthe response to that query matches both the voltage associated with themeasured test current and heater configuration and the typical voltagefor that region, then treatment is allowed to proceed.

In one embodiment of the present invention a manual switch (not shown),or alternately a logic switch, is used to set the APD machine to theappropriate, safe voltage for use. The instantaneous voltage is measuredand this measurement, either as the specific value or as a categoricaldescriptor, is displayed to the user. The user must respond that themeasured voltage is within the safe operating range for the machine ascurrently configured, or alternately must respond by altering theconfiguration of the machine, before power is allowed to flow to theheating element. The configuration could be altered electronically, forexample via the user interface computer 302, or could be performedmanually by flipping a switch.

In another embodiment of the present invention, a rectifier converts anyincoming alternating current (AC) into a single direct current (DC). Theheater circuit would resemble heater circuit 2005 in FIG. 49-8 exceptthe voltage detect 2020 element is replaced with a universal DC supplythat rectifies the AC voltage into a selected DC voltage. The electricalpower supplied to the heater elements 2001, 2002 may be modulated by aPWM element in the rectifier or by a separate PWM element 2030. Theheater circuit may include a safety relay 2010. The single voltage DCpower source allows the use of one heater configuration. The PWM elementin this embodiment may comprise one or more IGBT or an MOSFET switchesand related electrical hardware. In a preferred embodiment, the incomingalternating current would be converted to direct current in the range of12V to 48V.

In another embodiment, the heater element 2000 may comprise a PositiveTemperature Coefficient (PTC) element that self limits the powerdissipated. The internal electrical resistance of a PTC elementincreases with temperature, so the power level is self limiting. PTCheater elements are commercially available from companies such as STEGOthat are rated to run on voltages from 110 to 220 V rms. A heatercircuit employing a PTC heating element would resemble heater circuit2005 with the voltage detect element 2020 removed. The heater powerwould be controlled with the PWM element 2010 using a Triac.

Database and User Interface Systems

The database subsystem 346, also on the user interface computer 302,stores all data to and retrieves all data from the databases used forthe onboard storage of machine, patient, prescription, user-entry andtreatment history information. This provides a common access point whensuch information is needed by the system. The interface provided by thedatabase subsystem 346 is used by several processes for their datastorage needs. The database subsystem 346 also manages database filemaintenance and back-up.

The UI screen view 338 may invoke a therapy log query application tobrowse the therapy history database. Using this application, which mayalternatively be implemented as multiple applications, the user cangraphically review their treatment history, their prescription and/orhistorical machine status information. The application transmitsdatabase queries to the database subsystem 346. The application can berun while the patient is dialyzing without impeding the safe operationof the machine.

The remote access application, which may be implemented as a singleapplication or multiple applications, provides the functionality toexport therapy and machine diagnostic data for analysis and/or displayon remote systems. The therapy log query application may be used toretrieve information requested, and the data may be reformatted into amachine neutral format, such as XML, for transport. The formatted datamay be transported off-board by a memory storage device, direct networkconnection or other external interface 348. Network connections may beinitiated by the APD system, as requested by the user.

The service interface 356 may be selected by the user when a therapy isnot in progress. The service interface 356 may comprise one or morespecialized applications that log test results and optionally generate atest report which can be uploaded, for example, to a diagnostic center.The media player 358 may, for example, play audio and/or video to bepresented to a user.

According to one exemplary implementation, the databases described aboveare implemented using SQLite®, a software library that implements aself-contained, server-less, zero-configuration, transactional SQLdatabase engine.

The executive subsystem 332 implements two executive modules, the userinterface computer (UIC) executive 352 on the user interface computer302 and the automation computer (AC) executive 354 on the automationcomputer 300. Each executive is started by the startup scripts that runafter the operating system is booted and includes a list of processes itstarts. As the executives go through their respective process lists,each process image is checked to ensure its integrity in the file systembefore the process is launched. The executives monitor each childprocess to ensure that each starts as expected and continue monitoringthe child processes while they run, e.g., using Linux parent-childprocess notifications. When a child process terminates or fails, theexecutive either restarts it (as in the case of the UI view) or placesthe system in fail safe mode to ensure that the machine behaves in asafe manner. The executive processes are also responsible for cleanlyshutting down the operating system when the machine is powering off.

The executive processes communicate with each other allowing them tocoordinate the startup and shutdown of the various applicationcomponents. Status information is shared periodically between the twoexecutives to support a watchdog function between the processors. Theexecutive subsystem 332 is responsible for enabling or disabling thesafe line. When both the UIC executive 352 and the AC executive 354 haveenabled the safe line, the pump, the heater, and the valves can operate.Before enabling the lines, the executives test each line independentlyto ensure proper operation. In addition, each executive monitors thestate of the other's safe line.

The UIC executive 352 and the AC executive 354 work together tosynchronize the time between the user interface computer 302 and theautomation computer 300. The time basis is configured via a batterybacked real-time clock on the user interface computer 302 that isaccessed upon startup. The user interface computer 302 initializes theCPU of the automation computer 300 to the real-time clock. After that,the operating system on each computer maintains its own internal time.The executives work together to ensure sufficiently timekeeping byperiodically performing power on self tests. An alert may be generatedif a discrepancy between the automation computer time and the userinterface computer time exceeds a given threshold.

FIG. 47 shows the flow of information between various subsystems andprocesses of the APD system. As discussed previously, the UI model 360and cycler controller 362 run on the automation computer. The userinterface design separates the screen display, which is controlled bythe UI view 338, from the screen-to-screen flow, which is controlled bythe cycler controller 362, and the displayable data items, which arecontrolled by the UI model 360. This allows the visual representation ofthe screen display to be changed without affecting the underlyingtherapy software. All therapy values and context are stored in the UImodel 360, isolating the UI view 338 from the safety-critical therapyfunctionality.

The UI model 360 aggregates the information describing the current stateof the system and patient, and maintains the information that can bedisplayed via the user interface. The UI model 360 may update a statethat is not currently visible or otherwise discernable to the operator.When the user navigates to a new screen, the UI model 360 provides theinformation relating to the new screen and its contents to the UI view338. The UI model 360 exposes an interface allowing the UI view 338 orsome other process to query for current user interface screen andcontents to display. The UI model 360 thus provides a common point whereinterfaces such as the remote user interface and online assistance canobtain the current operational state of the system.

The cycler controller 362 handles changes to the state of the systembased on operator input, time and therapy layer state. Acceptablechanges are reflected in the UI model 360. The cycler controller 362 isimplemented as a hierarchical state machine that coordinates therapylayer commands, therapy status, user requests and timed events, andprovides view screen control via UI model 360 updates. The cyclercontroller 362 also validates user inputs. If the user inputs areallowed, new values relating to the user inputs are reflected back tothe UI view 338 via the UI model 360. The therapy process 368 acts as aserver to the cycler controller 362. Therapy commands from the cyclercontroller 362 are received by the therapy process 368.

The UI view 338, which runs on the UI computer 302, controls the userinterface screen display and responds to user input from the touchscreen. The UI view 338 keeps track of local screen state, but does notmaintain machine state information. Machine state and displayed datavalues, unless they are in the midst of being changed by the user, aresourced from the UI model 360. If the UI view 338 terminates and isrestarted, it displays the base screen for the current state withcurrent data. The UI view 338 determines which class of screens todisplay from the UI model 360, which leaves the presentation of thescreen to the UI view. All safety-critical aspects of the user interfaceare handled by the UI model 360 and cycler controller 362.

The UI view 338 may load and execute other applications 364 on the userinterface computer 302. These applications may perform non-therapycontrolling tasks. Exemplary applications include the log viewer, theservice interface, and the remote access applications. The UI view 338places these applications within a window controlled by the UI view,which allows the UI view to display status, error, and alert screens asappropriate. Certain applications may be run during active therapy. Forexample, the log viewer may be run during active therapy, while theservice interface and the remote access application generally may not.When an application subservient to the UI view 338 is running and theuser's attention is required by the ongoing therapy, the UI view 338 maysuspend the application and regain control of the screen and inputfunctions. The suspended application can be resumed or aborted by the UIview 338.

FIG. 48 illustrates the operation of the therapy subsystem 340 describedin connection with FIG. 46. The therapy subsystem 340 functionality isdivided across three processes: therapy control; therapy calculation;and solution management. This allows for functional decomposition, easeof testing, and ease of updates.

The therapy control module 370 uses the services of the therapycalculation module 372, solution management module 374 and machinecontrol subsystem 342 (FIG. 46) to accomplish its tasks.Responsibilities of the therapy control module 370 include trackingfluid volume in the heater bag, tracking fluid volume in the patient,tracking patient drain volumes and ultra filtrate, tracking and loggingcycle volumes, tracking and logging therapy volumes, orchestrating theexecution of the dialysis therapy (drain-fill-dwell), and controllingtherapy setup operations. The therapy control module 370 performs eachphase of the therapy as directed by the therapy calculation module 370.

The therapy calculation module 370 tracks and recalculates thedrain-fill-dwell cycles that comprise a peritoneal dialysis therapy.Using the patient's prescription, the therapy calculation module 372calculates the number of cycles, the dwell time, and the amount ofsolution needed (total therapy volume). As the therapy proceeds, asubset of these values is recalculated, accounting for the actualelapsed time. The therapy calculation module 372 tracks the therapysequence, passing the therapy phases and parameters to the therapycontrol module 370 when requested.

The solution management module 374 maps the placement of solution supplybags, tracks the volume in each supply bag, commands the mixing ofsolutions based upon recipes in the solution database, commands thetransfer of the requested volume of mixed or unmixed solution into theheater bag, and tracks the volume of mixed solutions available using thesolution recipe and available bag volume.

FIG. 49 shows a sequence diagram depicting exemplary interactions of thetherapy module processes described above during the initial ‘replenish’and ‘dialyze’ portions of the therapy. During the exemplary initialreplenish process 376, the therapy control module 370 fetches thesolution ID and volume for the first fill from the therapy calculationmodule 372. The solution ID is passed to the solution management module374 with a request to fill the heater bag with solution, in preparationfor priming the patient line and the first patient fill. The solutionmanagement module 374 passes the request to the machine controlsubsystem 342 to begin pumping the solution to the heater bag.

During the exemplary dialyze process 378, the therapy control module 370executes one cycle (initial drain, fill, dwell-replenish, and drain) ata time, sequencing these cycles under the control of the therapycalculation module 372. During the therapy, the therapy calculationmodule 372 is updated with the actual cycle timing, so that it canrecalculate the remainder of the therapy if needed.

In this example, the therapy calculation module 372 specifies the phaseas “initial drain,” and the therapy control module makes the request tothe machine control subsystem 342. The next phase specified by thetherapy calculation module 372 is “fill.” The instruction is sent to themachine control subsystem 342. The therapy calculation module 372 iscalled again by the therapy control module 370, which requests thatfluid be replenished to the heater bag during the “dwell” phase. Thesolution management module 374 is called by the therapy control module370 to replenish fluid in the heater bag by calling the machine controlsubsystem 342. Processing continues with therapy control module 370calling the therapy calculation module 372 to get the next phase. Thisis repeated until there are no more phases, and the therapy is complete.

Pump Monitor/Math Repeater

The Pump Monitor/Math Repeater process is a software process or functionthat runs on the automation computer 300 separate from the safetyexecutive 354. The Pump Monitor/Math Repeater process is implemented inas two separate threads or sub-functions that run independently. Themath repeater thread, herein referred to as the MR thread, confirms theFMS calculation result. The Pump Monitor thread, referred to as the PMthread, monitors the net fluid and air flow across relevant endpointsfrom information provided in the routine status messages from theMachine process 342. The relevant endpoints may include but not belimited to 5 potential bag spikes, the heater bag, patient port anddrain port. The PM thread will also monitor the heater pan temperaturevia information from the IO Server process. The PM thread will signal analarm to the safety executive 354, if predefined limits for fluid flow,air flow or temperature are exceeded.

The MR thread accepts the high speed pressure data and repeats the FMScalculation described above to recalculate the fluid volume displaced.The MR thread compares its recalculated fluid volume to the volumecalculated by the Machine process 342 and sends a message to the safetyexecutive. In another example, the MR thread declares and errorcondition if the two fluid volume values do not match.

The PM thread monitors several aspects of the pumping process as asafety check on the functioning of the cycler 14. The PM thread willdeclare an invalid pump operation error condition if the HardwareInterface 310 reports valves open that do not correspond to thecommanded pump action by the Machine subsystem 342. An example of aninvalid valve condition would be if any port valve 186, 184 (FIG. 6) areopen, while the pump was in an idle mode. The state of valves in thecassette is mapped to the state of the corresponding pneumatic valves2710, which are energized by the hardware interface 310. Another exampleof an invalid valve condition would be a port valve 184, 186 that isopen that does not correspond to the specified source of sink of fluid.

The PM thread will declare an error condition if excess fluid is pumpedto the patient while the heater button temperature sensor 506 reportsless than a given temperature. In a preferred embodiment, the PM threadwill declare a error condition more than 50 ml of fluid is pumped to thepatient while the button temperature is less than 32° C.

The PM thread will maintain a numerical accumulator on the amount offluid pumped to the patient. If total volume of fluid pumped to thepatient exceeds a specified amount, the PM thread will declare an error.The specified amount may be defined in the prescription information andmay include an additional volume equal to one chamber volume orapproximately 23 ml.

The PM thread will maintain a numerical accumulator on the amount of airmeasured in the pumping chamber by the FMS method for air taken fromeach bag. If the total amount of air from any bag exceeds the maximumallowed volume of air for that bag, then the PM thread will declare anerror. In a preferred embodiment, the maximum allowed air volume for theheater bag is 350 ml and the maximum allowed air volume for a supply bagis 200 ml. A large air volume from a bag indicates that it may contain aleak to the atmosphere. The maximum allowed air volume for the heaterbag may be larger to account for out-gassing when the fluid is heated.

Alert/Alarm Functions

Conditions or events in the APD system may trigger alerts and/or alarmsthat are logged, displayed to a user, or both. These alerts and alarmsare a user interface construct that reside in the user interfacesubsystem, and may be triggered by conditions that occur in any part ofthe system. These conditions may be grouped into three categories: (1)system error conditions, (2) therapy conditions, and (3) systemoperation conditions.

“System error conditions” relate to errors detected in software, memory,or other aspects of the processors of the APD system. These errors callthe reliability of the system into question, and may be considered“unrecoverable.” System error conditions cause an alarm that isdisplayed or otherwise made known to the user. The alarm may also belogged. Since system integrity cannot be guaranteed in the instance of asystem error condition, the system may enter a fail safe mode in whichthe safe line described herein is disabled.

Each subsystem described in connection with FIG. 46 is responsible fordetecting its own set of system errors. System errors between subsystemsare monitored by the user interface computer executive 352 andautomation computer executives 354. When a system error originates froma process running on the user interface computer 302, the processreporting the system error terminates. If the UI screen view subsystem338 is terminated, the user interface computer executive 352 attempts torestart it, e.g., up to a maximum of three times. If it fails to restartthe UI screen view 338 and a therapy is in progress, the user interfacecomputer executive 352 transitions the machine to a fail safe mode.

When a system error originates from a process running on the automationcomputer 300, the process terminates. The automation computer executive354 detects that the process has terminated and transitions to a safestate if a therapy is in progress.

When a system error is reported, an attempt is made to inform the user,e.g., with visual and/or audio feedback, as well as to log the error toa database. System error handling is encapsulated in the executivesubsystem 332 to assure uniform handling of unrecoverable events. Theexecutive processes of the UIC executive 352 and AC executive 354monitor each other such that if one executive process fails duringtherapy, the other executive transitions the machine to a safe state.

“Therapy conditions” are caused by a status or variable associated withthe therapy going outside of allowable bounds. For example, a therapycondition may be caused by an out-of-bounds sensor reading. Theseconditions may be associated with an alert or an alarm, and then logged.Alarms are critical events, generally requiring immediate action. Alarmsmay be prioritized, for example as low, medium or high, based on theseverity of the condition. Alerts are less critical than alarms, andgenerally do not have any associated risk other than loss of therapy ordiscomfort. Alerts may fall into one of three categories: messagealerts, escalating alerts, and user alerts.

The responsibility for detecting therapy conditions that may cause analarm or alert condition is shared between the UI model and therapysubsystems. The UI model subsystem 360 (FIG. 47) is responsible fordetecting alarm and alert conditions pre-therapy and post-therapy. Thetherapy subsystem 340 (FIG. 46) is responsible for detecting alarm andalert conditions during therapy.

The responsibility for handling alerts or alarms associated with therapyconditions is also shared between the UI model and therapy subsystems.Pre-therapy and post-therapy, the UI model subsystem 360 is responsiblefor handling the alarm or alert condition. During a therapy session, thetherapy subsystem 340 is responsible for handling the alarm or alertcondition and notifying the UI Model Subsystem an alarm or alertcondition exists. The UI model subsystem 360 is responsible forescalating alerts, and for coordinating with the UI view subsystem 338to provide the user with visual and/or audio feedback when an alarm oralert condition is detected.

“System operation conditions” do not have an alert or alarm associatedwith them. These conditions are simply logged to provide a record ofsystem operations. Auditory or visual feedback need not be provided.

Actions that may be taken in response to the system error conditions,therapy conditions, or system operation conditions described above areimplemented by the subsystem (or layer) that detected the condition,which sends the status up to the higher subsystems. The subsystem thatdetected the condition may log the condition and take care of any safetyconsiderations associated with the condition. These safetyconsiderations may comprise any one or combination of the following:pausing the therapy and engaging the occluder; clearing states andtimers as needed; disabling the heater; ending the therapy entirely;deactivating the safe line to close the occluder, shut off the heater,and removing power from the valves; and preventing the cycler fromrunning therapies even after a power cycle to require the system to besent back to service. The UI subsystem 334 may be responsible forconditions that can be cleared automatically (i.e., non-latchingconditions) and for user recoverable conditions that are latched and canonly be cleared by user interaction.

Each condition may be defined such that it contains certain informationto allow the software to act according to the severity of the condition.This information may comprise a numeric identifier, which may be used incombination with a lookup table to define priority; a descriptive nameof the error (i.e., a condition name); the subsystem that detected thecondition; a description of what status or error triggers the condition;and flags for whether the condition implements one or more actionsdefined above.

Conditions may be ranked in priority such that when multiple conditionsoccur, the higher priority condition may be handled first. This priorityranking may be based on whether the condition stops the administrationof therapy. When a condition occurs that stops therapy, this conditiontakes precedence when relaying status to the next higher subsystem. Asdiscussed above, the subsystem that detects a condition handles thecondition and sends status information up to the subsystem above. Basedon the received status information, the upper subsystem may trigger adifferent condition that may have different actions and a differentalert/alarm associated with it. Each subsystem implements any additionalactions associated with the new condition and passes status informationup to the subsystem above. According to one exemplary implementation,the UI subsystem only displays one alert/alarm at a given time. In thiscase, the UI model sorts all active events by their priority anddisplays the alert/alarm that is associated with the highest priorityevent.

A priority may be assigned to an alarm based on the severity thepotential harm and the onset of that harm. Table 1, below, shows anexample of how priorities may be assigned in this manner

TABLE 1 POTENTIAL RESULT OF FAILURE TO RESPOND TO THE CAUSE OF ALARMONSET OF POTENTIAL HARM CONDITION IMMEDIATE PROMPT DELAYED death orirreversible high priority high priority medium priority injuryreversible injury high priority medium priority low priority minordiscomfort or medium priority low priority low priority or no injuryalarm signal

In the context of Table 1, the onset of potential harm refers to when aninjury occurs and not to when it is manifested. A potential harm havingan onset designated as “immediate” denotes a harm having the potentialto develop within a period of time not usually sufficient for manualcorrective action. A potential harm having an onset designated as“prompt” denotes a harm having the potential to develop within a periodof time usually sufficient for manual corrective action. A potentialharm having an onset designated as “delayed” denotes a harm having thepotential to develop within an unspecified time greater than that givenunder “prompt.”

-   -   FIGS. 50-55 show exemplary screen views relating to alerts and        alarms that may be displayed on a touch screen user interface.        FIG. 50 shows the first screen of an alarm, which includes a        diagram 380 and text 382 instructing a user to close their        transfer set. The screen includes a visual warning 384, and is        also associated with an audio warning. The audio warning may be        turned off my selecting the “audio off” option 386 on the touch        screen. When the user has closed the transfer set, the user        selects the “confirm” option 388 on the touch screen. FIG. 51        shows a similar alarm screen instructing a user to close their        transfer set. In this case, an indication that draining is        paused 390 and an instruction to select “end treatment” are        provided 392.

As previously discussed, alerts generally do not have associated riskother than loss of therapy or discomfort. Thus, an alert may or may notcause the therapy to pause. Alerts can be either “auto recoverable,”such that if the event clears the alert automatically clears, or “userrecoverable,” such that user interaction with the user interface isneeded to clear the alert. An audible alert prompt, which may have avolume that may be varied within certain limits, may be used to bring analert to the attention of a user. In addition, information or aninstruction may be displayed to the user. So that such information orinstruction may be viewed by the user, an auto-dim feature of the userinterface may be disabled during alerts.

In order to reduce the amount of disturbance the user, alerts may becategorized into different types based on how important an alert is andhow quick a user response is required. Three exemplary types of alertsare a “message alert,” an “escalating alert,” and a “user alert.” Thesealerts have different characteristics based on how information isvisually presented to the user and how the audible prompt is used.

A “message alert” may appear at the top of a status screen and is usedfor informational purposes when a user interaction is not required.Because no action needs to be taken to clear the alert, an audibleprompt is generally not used to avoid disturbing, and possibly waking,the patient. However, an audible alert may be optionally presented. FIG.52 shows an exemplary message alert. In particular, FIG. 52 shows anunder-temperature message alert 394 that may be used to inform a userwhen the dialysate is below a desired temperature or range. In thiscase, a user does not need to take any action, but is informed thattherapy will be delayed while the dialysate is heated. If the patientdesires more information, the “view” option 396 may be selected on thetouch screen. This causes additional information 398 concerning thealert to appear on the screen, as shown in FIG. 53. A message alert mayalso be used when there is a low flow event that the user is trying tocorrect. In this case, a message alert may be displayed until the lowflow event is cleared to provide feedback to the user on whether theuser fixed the problem.

An “escalating alert” is intended to prompt the user to take action in anon-jarring manner During an escalating alert, a visual prompt maydisplayed on the touch screen and an audible prompt may be presented(e.g., once). After a given period of time, if the event that caused thealert is not cleared, a more emphatic audible prompt may be presented.If the event causing the alert is not cleared after an additional periodof time, the alert is escalated to a “user alert.” According to oneexemplary implementation of a user alert, a visual prompt is displayeduntil the alert is cleared and an audible prompt, which can be silenced,is presented. The UI subsystem does not handle the transition to fromescalating alert to user alert. Rather, the subsystem that triggered theoriginal event will trigger a new event associated with the user alert.FIG. 54 shows a screen view displaying information concerning anescalating alert. This exemplary alert includes an on-screen alertmessage 400 and a prompt 402 instructing the user to check the drainline for kinks and closed clamps, as well as and an audible prompt. Theaudible prompt may be continuous until it is silenced by the user. FIG.55 shows a screen view including an “audio off” option 404 that may beselected to silence the audible prompt. This alert can be used directly,or as part of the escalating alert scheme.

Each alert/alarm is specified by: an alert/alarm code, which is a uniqueidentifier for the alert/alarm; an alert/alarm name, which is adescriptive name of the alert/alarm; an alert/alarm type, whichcomprises the type of alert or level of alarm; an indication of whetheran audible prompt is associated with the alert/alarm; an indication ofwhether the alert and associated event can be bypassed (or ignored) bythe user; and the event code of the event or events that trigger thealert/alarm.

During alarms, escalating alerts and user alerts, the event code (whichmay be different from the alert or alarm code, as described above) maybe displayed on the screen so that the user can read the code to servicepersonnel if needed. Alternatively or additionally, a voice guidancesystem may be used so that, once connected to a remote call center, thesystem can vocalize pertinent information about the systemconfiguration, state, and error code. The system may be connected to theremote call center via a network, telephonic connection, or some othermeans.

An example of a condition detected by the therapy subsystem is describedbelow in connection with FIG. 56. The condition results when the APDsystem is not positioned on a level surface, which is important for airmanagement. More particularly, the condition results when a tilt sensordetects that APD system is tilted beyond a predetermined threshold, suchas 35°, with respect to a horizontal plane. As described below, arecoverable user alert may be generated by the therapy subsystem if thetilt sensor senses an angle with an absolute value greater than thepredetermined threshold. To avoid nuisance alarms, the user may bedirected to level the APD system before therapy begins. The tiltthreshold may be lower during this pre-therapy period (e.g., 35°). Theuser may also be given feedback concerning whether the problem iscorrected.

When the tilt sensor detects an angle of tilt exceeding a thresholdvalue during therapy, the machine subsystem 342 responds by stopping thepump in a manner similar to detecting air in the pump chamber. Thetherapy subsystem 340 asks for status and determines that the machinelayer 342 has paused pumping due to tilt. It also receives statusinformation concerning the angle of the machine. At this point, thetherapy subsystem 340 generates a tilt condition, pauses therapy, andsends a command to the machine subsystem 342 to pause pumping. Thiscommand triggers clean-up, such as taking fluid measurement system (FMS)measurements and closing the patient valve. The therapy subsystem 340also starts a timer and sends an auto recoverable tilt condition up tothe UI model 360, which sends the condition to the UI view 338. The UIview 338 maps the condition to an escalating alert. The therapysubsystem 340 continues to monitor the tilt sensor reading and, if itdrops below the threshold, clears the condition and restarts therapy. Ifthe condition does not clear before the timer expires, the therapysubsystem 340 triggers a user recoverable “tilt timeout” condition thatsupersedes the auto-recoverable tilt condition. It sends this conditionto the UI model 360, which sends the condition to the UI view 338. TheUI view 338 maps the condition to a user alert. This condition cannot becleared until a restart therapy command is received from the UIsubsystem (e.g., the user pressing the resume button). If the tiltsensor reading is below the threshold, the therapy resumes. If it is notbelow the threshold, the therapy layer triggers an auto recoverable tiltcondition and starts the timer.

Prioritized Audible Signals

The cycler may provide audible signals and voice guidance to the user tocommunicate a range of information including but not limited to numberselection, sound effects (button selection, action selection), machinecondition, operational directions, alerts, and alarms. The cyclercontroller 16 may cause a speaker to annunciate audible signals andvocalizations from stored sound files stored in memory on one or both ofthe computers 300, 302 in the control system 16. Alternatively,vocalizations may be stored and produced by a specialized voice chip.

In some instances, the cycler may have multiple audible signals toannunciate at the same time or sequentially in a very short time. Theannunciation of several signals in a short period of time may overwhelmthe user resulting in annoyance or the loss of critical safetyinformation. The cycler controller 16 may assign priorities to eachaudible signal and suppress the lower priority signals to allow theclear communication of higher priority audible signals. In one instance,the audible signals are prioritized from the highest priority alarmsignals to the lowest priority annunciation of a sequence of numbers:

1. Alarms

2. Alerts

3. Sound Effects

4. Voice Guidance

5. Annunciation for a sequence of numbers.

Alarms and alerts are described above. Sound effects may confirm soundsto indicate that a button, or choice has been selected. Sound effectsmay also announce or confirm a particular action is being taken by thecycler. Voice guidance may include voiced instructions to execute aparticular procedure, access help, contact a call center and otherdirecting instructions. Annunciation for a sequence of numbers mayinclude reading back to the user or the call center the number that theuser had just keyed in or it may read the user allowable values forrequested input.

Audible Sleep Aid

The cycler 14 may include an option to play soothing sounds at night toaid sleeping. The playing of sounds such as rain, ocean waves, etc arereferred to as sound therapy. Sound therapy for sleep can provide someusers with a higher tolerance for nighttime noises and the masking orreplacing of nighttime noise with more rhythmic, soothing sounds thatminimize sleep disturbance. Sound therapy may help individuals sufferingfrom hearing conditions such as hyperacusis and tinnitus. The userinterface 324 may provide the user with a menu to select types of sound,volume levels and duration so that the sound therapy can play beforeduring the initial period of sleep. The sound files may be stored in thememories of the computers 300, 302 and played by the speaker in thecycler 14. In another example, the cycler may include an output jack todrive external speakers. In another example, the sound files and/or thespeaker driver electronics may be separate from either the automationcomputer 300 or the user interface computer 302. The sound files mayinclude the but be limited to rain sounds, thunder storms, ocean waves,thunder, forest sounds, crickets, white noise, and pink noise (varyingamplitude and more bass).

Battery Operation

The cycler may include a rechargeable lithium ion battery for use as abackup power source. At a minimum this battery helps to ensure that thecycler does not turn off without alerting the user and saving thecurrent state of the treatment. A power management system may beimplemented by the cycler when on battery power that is contingent onthe amount of charge remaining in the battery. If the battery issufficiently charged, the cycler can prevent brownouts or short poweroutages from interfering with the completion of a therapy. The cyclercontrol circuitry can measure the state of charge of the battery, andcan correlate the battery charge level with operable states. Thisinformation may be obtained empirically through testing, and thecorrelations between battery charge level and the ability to operate thevarious subsystems may be stored in memory. The following functions maybe associated with the battery charge level:

Level 4: Enough power to perform one cycle of therapy. Implemented if,for example, the charge level of the battery is equal to or greater thanapproximately 1100 milliamp-hours.Level 3: Enough power to perform a user drain. Implemented if, forexample, the charge level of the battery is equal to or greater thanapproximately 500 milliamp-hours.Level 2: Enough power to end therapy, display alert, and guide userthrough post-therapy breakdown. Implemented if, for example, the chargelevel of the battery is equal to or greater than approximately 300milliamp-hours.Level 1: Enough power to end therapy and display an alert. Implementedif, for example, the charge level of the battery is equal to or greaterthan approximately 200 milliamp-hours.Level 0: Not enough power to operate.If there is enough charge in the battery (Level 4), the cycler willcontinue with the therapy until the current cycle is finished. This maynot include replenishing the heater bag or heating the solution.Therefore, if already in a fill phase, the cycler may continue thetherapy if the solution in the heater bag is in the proper temperaturerange and there is enough solution in the heater bag. If the batteryonly has enough capacity to perform a 20 minute drain (Level 3), thecycler will alert the user, and give the user the option to either drainor end treatment without draining. If the battery only has enough powerto alert the user (Level 2) it will not give the user the option todrain and the user will be guided through the post-therapy breakdown. Ifthere is not enough power to guide the user through breakdown (Level 1),the user will be prompted to disconnect and then the cycler will powerdown. At this battery level the cycler may not have enough power torelease the door, so the user may not be able to breakdown the therapy.During start up, the cycler can assess the state of the batter, andalert the user if the battery has a fault or if the battery does nothave a sufficient charge to at least alert the patient if main power islost. The cycler may be programmed to not allow the user to start atreatment without the battery having enough capacity to provide andalert and guide the user through post-therapy breakdown (Battery Level2).Another example of battery charge levels and available therapy choicesor machine actions sets 4 battery charge levels and the availabletherapy choices or machine actions:

Level 4:

If the fill process has not started, then suspend operation until the ACpower is restored. The suspend is limited to 30 mins.

If the fill process has started, then complete cycle including the fill,dwell and drain processes.

The heater bag will not be refilled as there is no heating duringbattery operation.

End therapy, and guide user through post-therapy breakdown includingremoval of the of the dialysate delivery set 12 a from the cycler 14.

Level 3:

If in the fill or drain process, then suspend operation until the ACpower is restored. The suspend is limited to 30 mins.

If the drain process has started, then complete the cycle.

The heater bag will not be refilled as there is no heating duringbattery operation.

End therapy, and guide user through post-therapy breakdown includingremoval of the of the dialysate delivery set 12 a from the cycler 14.

Level 2:

End therapy, and guide user through post-therapy breakdown includingremoval of the of the dialysate delivery set 12 a from the cycler 14.

Level 1:

End therapy.

Level 0:

Not enough power to operate.

An alert will be displayed to the user or patient at levels 1-4. Thecontrol system 16 may extend the cycler operation on battery power bydimming the display screen 324 after a given time period from the lastscreen touch. In another example the display screen 324 may dim after agiven period from the appearance of the most recent message, alert orwarning. In one example, the display screen 324 will dim 2 minutes afterthe more recent screen touch or last. The display screen 324 may includea message or symbol indicating operation on battery power.

The electrical circuitry connecting the battery to the pneumatic valvesmay include a regulated voltage boost converter that steps-up thesupplied variable battery voltage to a consistent voltage. The suppliedbattery voltage may drop as the battery is discharged, In one example,an Li-Ion battery at full charge may supply 12.3 volts. The suppliedvoltage may drop as the battery is depleted to as low as 9 volts whenthe battery is fully discharged. The pneumatic valves may require aminimum voltage to reliably open fully. In one example, the minimumvoltage to reliably open the valve may be 12 volts.

A regulated voltage boost converter may be placed between the supplybatter and the valves to assure sufficient voltage to reliably open thevalves as battery discharges. The regulated voltage boost converter willoutput a regulated voltage at a higher value than the variable batteryvoltage input. In one example, the regulated voltage boost converter maybe an integrated chip such as the TPS61175 made by Texas Instruments. Aregulated voltage buck/boost converter may also be used between thebattery and the valves. The buck/boost converter is able to supply aregulated voltage output from supplied voltages that are higher, equalto, or lower than the input voltage.

In one embodiment, the PWM duty cycle of the valve drivers may vary withthe measured battery voltage. The valves may be operated in apick-and-hold manner, where an initially higher voltage is applied toopen the valve and then a lower voltage is applied to hold the valve indesired condition. The PWM duty cycle for the hold function may bescaled inversely with the measure battery voltage to provide aconsistent averaged voltage or current to the valves. The PWM duty cyclemay be scaled inversely with measured battery voltage for the highervoltage open or pick operation.

Screen Display

As discussed previously, the UI view subsystem 338 (FIG. 47) isresponsible for the presentation of the interface to the user. The UIview subsystem is a client of and interfaces with the UI model subsystem360 (FIG. 47) running on the automation computer. For example, the UIview subsystem communicates with the UI model subsystem to determinewhich screen should be displayed to the user at a given time. The UIview may include templates for the screen views, and may handlelocale-specific settings such as display language, skin, audio language,and culturally sensitive animations.

There are three basic types of events that occur in the UI viewsubsystem. These are local screen events that are handled by theindividual screens, model events in which a screen event must propagatedown to the UI model subsystem, and polling events that occur on a timerand query the UI model subsystem for status. A local screen event onlyaffects the UI view level. These events can be local screen transitions(e.g., in the case of multiple screens for a single model state),updates to view settings (e.g., locality and language options), andrequests to play media clips from a given screen (e.g., instructionalanimations or voice prompts). Model events occur when the UI viewsubsystem must consult with the UI model subsystem to determine how tohandle the event. Examples that fall into this category are theconfirmation of therapy parameters or the pressing of the “starttherapy” button. These events are initiated by the UI view subsystem,but are handled in the UI model subsystem. The UI model subsystemprocesses the event and returns a result to the UI view subsystem. Thisresult drives the internal state of the UI view subsystem. Pollingevents occur when a timer generates a timing signal and the UI modelsubsystem is polled. In the case of a polling event, the current stateof the UI view subsystem is sent to the UI model subsystem forevaluation. The UI model subsystem evaluates the state information andreplies with the desired state of the UI view subsystem. This mayconstitute: (1) a state change, e.g., if the major states of the UImodel subsystem and the UI view subsystem are different, (2) a screenupdate, e.g., if values from the UI model subsystem change valuesdisplayed on-screen, or (3) no change in state, e.g., if the state ofthe UI model subsystem and the UI view subsystem are identical. FIG. 57shows the exemplary modules of the UI view subsystem 338 that performthe functions described above.

As shown in FIG. 57, the UI model client module 406 is used tocommunicate events to the UI model. This module 406 is also used to pollthe UI model for the current status. Within a responsive status message,the UI model subsystem may embed a time to be used to synchronize theclocks of the automation computer and the user interface computer.

The global slots module 408 provides a mechanism by which multiplecallback routines (slots) can subscribe to be notified when given events(signals) occur. This is a “many-to-many” relationship, as a slot can bebound to many signals, and likewise a signal can be bound to many slotsto be called upon its activation. The global slots module 408 handlesnon-screen specific slots, such as application level timers for UI modelpolling or button presses that occur outside of the screen (e.g., thevoice prompt button).

The screen list class 410 contains a listing of all screens in the formof templates and data tables. A screen is made up of a template and anassociated data table that will be used to populate that screen. Thetemplate is a window with widgets laid out on it in a generic manner andwith no content assigned to the widgets. The data table includes recordsthat describe the content used to populate the widgets and the state ofthe widgets. A widget state can be checked or unchecked (in the case ofa checkbox style widget), visible or hidden, or enabled or disabled. Thedata table can also describe the action that occurs as a result of abutton press. For example, a button on window ‘A’ derived from template‘1’ could send an event down to the UI model, whereas that same buttonon window ‘B’ also derived from template ‘1’ could simply cause a localscreen transition without propagating the event down to the UI model.The data tables may also contain an index into the context-sensitivehelp system.

The screen list class 410 forwards data from the UI model to theintended screen, selects the proper screen-based data from the UI model,and displays the screen. The screen list class 410 selects which screento display based on two factors: the state reported by the UI model andthe internal state of the UI view. In some cases, the UI model may onlyinform the UI view that it is allowed to display any screen within acategory. For example, the model may report that the machine is idle(e.g., no therapy has been started or the setup phase has not yetoccurred). In this case, it is not necessary to confer with the UI modelwhen the user progresses from a menu into its sub-menu. To track thechange, the UI view will store the current screen locally. This localsequencing of screens is handled by the table entries described above.The table entry lists the actions that respective buttons will initiatewhen pressed.

The language manager class 412 is responsible for performing inventoryon and managing translations. A checksum may be performed on the list ofinstalled languages to alert the UI view if any of the translations arecorrupted and or missing. Any class that wants a string translated asksthe language manager class 412 to perform it. Translations may behandled by a library (e.g., Qt®). Preferably, translations are requestedas close as possible to the time of rendering. To this end, most screentemplate member access methods request a translation right beforehanding it to the widget for rendering.

A skin comprises a style-sheet and images that determine the “look andfeel” of the user interface. The style-sheet controls things such asfonts, colors, and which images a widget will use to display its variousstates (normal, pressed, disabled, etc.). Any displayed widget can haveits appearance altered by a skin change. The skin manager module 414 isresponsible for informing the screen list and, by extension, the screenwidgets, which style-sheet and skin graphics should be displayed. Theskin manager module 414 also includes any animated files the applicationmay want to display. On a skin change event, the skin manager willupdate the images and style-sheet in the working set directory with theproper set, which is retrieved from an archive.

The video manager module 416 is responsible for playinglocale-appropriate video given a request to display a particular video.On a locale change event, the video manager will update the videos andanimations in the working set directory with the proper set from anarchive. The video manager will also play videos that have accompanyingaudio in the audio manager module 418. Upon playback of these videos,the video manager module 416 will make the appropriate request to theaudio manager module 418 to play the recording that belongs to theoriginally requested video clip.

Similarly, the audio manager module 418 is responsible for playinglocale-appropriate audio given a request to play a particular audioclip. On a locale change event, the audio manager will update the audioclips in the working set directory with the proper set from an archive.The audio manager module 418 handles all audio initiated by the UI view.This includes dubbing for animations and sound clips for voice prompts.

The database client module 420 is used to communicate with the databasemanager process, which handles the interface between the UI viewsubsystem and the database server 366 (FIG. 47). The UI view uses thisinterface to store and retrieve settings, and to supplement therapy logswith user-provided answers to questions about variables (e.g., weightand blood pressure).

The help manager module 422 is used to manage the context-sensitive helpsystem. Each page in a screen list that presents a help button mayinclude an index into the context-sensitive help system. This index isused so that the help manager can display the help screen associatedwith a page. The help screen may include text, pictures, audio, andvideo.

The auto ID manager 424 is called upon during pre-therapy setup. Thismodule is responsible for capturing an image (e.g., a photographicimage) of a solution bag code (e.g., a datamatrix code). The dataextracted from the image is then sent to the machine control subsystemto be used by the therapy subsystem to identify the contents of asolution bag, along with any other information (e.g., origin) includedin the code.

Using the modules described above, the UI view subsystem 338 renders thescreen views that are displayed to the user via the user interface(e.g., display 324 of FIG. 45). FIGS. 58-64 show exemplary screen viewsthat may be rendered by the UI view subsystem. These screen viewsillustrate, for example, exemplary input mechanisms, display formats,screen transitions, icons and layouts. Although the screens shown aregenerally displayed during or before therapy, aspects of the screenviews may be used for different input and output functions than thoseshown.

The screen shown in FIG. 58 is an initial screen that provides the userthe option of selecting between “start therapy” 426 to initiate thespecified therapy 428 or “settings” 430 to change settings. Icons 432and 434 are respectively provided to adjust brightness and audio levels,and an information icon 436 is provided to allow the user to solicitmore information. These icons may appear on other screens in a similarmanner.

FIG. 59 shows a status screen that provides information the status ofthe therapy. In particular, the screen indicates the type of therapybeing performed 438, the estimated completion time 440, and the currentfill cycle number and total number of fill cycles 442. The completionpercentage of the current fill cycle 444 and the completion percentageof the total therapy 446 are both numerically and graphically displayed.The user may select a “pause” option 448 to pause therapy.

FIG. 60 shows a menu screen with various comfort settings. The menuincludes brightness arrows 450, volume arrows 452 and temperature arrows454. By selecting either the up or down arrow in each respective pair, auser can increase or decrease screen brightness, audio volume, and fluidtemperature. The current brightness percentage, volume percentage andtemperature are also displayed. When the settings are as desired, a usermay select the “OK” button 456.

FIG. 61 shows a help menu, which may be reached, for example, bypressing a help or information button on a prior screen. The help menumay include text 458 and/or an illustration 460 to assist the user. Thetext and/or illustration may be “context sensitive,” or based on thecontext of the prior screen. If the information provided to the usercannot conveniently be provided in one screen, for example in the caseof a multi-step process, arrows 462 may be provided to allow the user tonavigate backward and forward between a series of screens. When the userhas obtained the desired information. he or she may select the “back”button 464. If additional assistance is required, a user may select the“call service center” option 466 to have the system contact the callservice center.

FIG. 62 illustrates a screen that allows a user to set a set ofparameters. For example, the screen displays the current therapy mode468 and minimum drain volume 470, and allows a user to select theseparameters to be changed. Parameters may be changed in a number of ways,such as by selecting a desired option from a round robin style menu onthe current screen. Alternatively, when the user selects a parameter tobe changed, a new screen may appear, such as that shown in FIG. 63. Thescreen of FIG. 63 allows a user to adjust the minimum drain volume byinputting a numeric value 472 using a keypad 474. Once entered, the usermay confirm or cancel the value using buttons 476 and 478. Referringagain to FIG. 62, a user may then use the “back” and “next” arrows 480,482 to navigate through a series of parameters screens, each including adifferent set of parameters.

Once all desired parameters have been set or changed (e.g., when theuser has navigated through the series of parameters screens), a screensuch as that shown in FIG. 64 may be presented to allow a user to reviewand confirm the settings. Parameters that have changed may optionally behighlighted in some fashion to draw the attention of the user. When thesettings are as desired, a user may select the “confirm” button 486.

Automated Peritoneal Dialysis Therapy Control

Continuous ambulatory peritoneal dialysis (“CAPD”) is traditionallyperformed manually, with a patient or user transferring dialysissolution from a bag into his or her peritoneal cavity, having the fluiddwell in the abdomen for three to six hours, and then allowing the fluidto empty into a collection or drain bag. This is typically done three orfour times a day. Automated peritoneal dialysis (“APD”) differs fromCAPD in that APD is achieved with the aid of a peritoneal dialysismachine (“cycler”) that performs a series of fill-dwell-drain cyclesduring a period of several hours (e.g. when asleep or at night). In APD,the fluid introduced during a fill phase of a cycle, plus anyultrafiltration fluid, may not drain completely during the followingdrain phase of the cycle. This may be a result of the user's position inbed, leading to sequestration of fluid, for example, in a recess in theperitoneal cavity, and preventing an indwelling catheter from accessingall of the fluid present. In continuous cycling peritoneal dialysis(“CCPD”), the cycler attempts to perform a full drain after a fill anddwell phase in order to prevent accumulation of retained fluid (aresidual intraperitoneal volume) with each succeeding cycle. APDgenerally comprises a plurality of short nighttime exchanges ofdialysate while the user is connected to the cycler and asleep. At theend of a nighttime therapy, a volume of dialysis fluid—possibly ofdifferent composition—may be left in the peritoneal cavity during theday for continued exchange of solutes, transfer of waste compounds, andultrafiltration. In intermittent peritoneal dialysis (“IPD”), multipleexchanges of dialysate are performed over a period of time (e.g., atnight), without having a prolonged residual (or daytime) dwell cycle.

Therapy with a cycler generally begins with an initial drain phase toattempt to ensure that the peritoneal cavity is empty of fluid. Thecharacteristics of the dialysate solution usually cause some transfer offluid from the patient's tissues to the intraperitonealspace—ultrafiltration. As therapy proceeds through a series of cycles,fluid may accumulate in the intraperitoneal cavity if the drain phasedoes not yield the volume of fluid infused during the fill phase, plusthe volume of ultrafiltered fluid produced during the time thatdialysate solution is in the peritoneal cavity. In some modes, thecycler may be programmed to issue an alarm to the user when the drainvolume has not matched the volume of fluid infused plus the expectedultrafiltration (“UF”) volume. (The expected UF volume is a functionof—among other things—the individual patient's physiology, the chemicalcomposition of the dialysate solution, and the time during which thedialysate solution is expected to be present in the peritoneal cavity).

In other modes, the cycler may proceed to the next fill-dwell-draincycle if a pre-determined amount of drain time has passed and apre-determined minimum percentage (e.g. 85%) of the preceding fillvolume has been drained. In this case, the cycler may be programmed toalarm if the drain flow decreases below a pre-determined rate after theminimum drain time and before the minimum drain percentage has beenreached. The cycler may be programmed to alert the user after severalminutes (e.g., two minutes) of attempting but failing to maintain apre-determined flow rate when pumping fluid from the peritoneal cavity.A low-flow condition may be detectable by the cycler because of theincreased amount of time required to fill a pump chamber beforeend-of-stroke is detected by the controller. A zero-flow or no-flowcondition may be detectable by the cycler because of the detection bythe controller of a premature end-of-stroke state. The duration of thetime delay before alerting the user or initiating a new fill-dwell-draincycle may be programmed to be a few minutes in a low-flow condition(e.g., 2 minutes), and may be shorter (e.g., 30 seconds) in a no-flowcondition. A shorter wait-time during a no-flow condition may bepreferable, for example, because it may be associated with a greaterdegree of patient discomfort, or may be the result of a quicklycorrectable problem, such as a bend in the patient line or catheter.This time delay may be programmed at the cycler manufacturing stage ormay be selectable by a clinician as a prescription parameter. The extentof the delay may be governed, among other things, by the countervailingdesire of the user or clinician to stay within the targeted totaltherapy time (keeping in mind that little dialysis is likely to occurwhen the intraperitoneal volume (“IPV”) is low or close to zero). If afull drain is not achieved, the cycler may also track the amount offluid estimated to be accumulating with each cycle, and issue a warningor alarm if the cumulative IPV exceeds a pre-determined amount. Thismaximum IPV may be a parameter of the therapy prescription programmedinto the cycler by the clinician, taking account of the particularphysiological characteristics of the individual patient/user.

One method of dealing with the cumulative retention of fluid during aseries of CCPD cycles is to convert the CCPD therapy to a tidalperitoneal dialysis (“TPD”) therapy. TPD generally comprises afill-dwell-drain cycle in which a drain volume is intentionally made aprescribed fraction of the initial fill volume (which may also beinitially be entered by the clinician as a prescription parameter). Apre-determined percentage of the infused fluid, or a pre-determinedamount of fluid is arranged to remain in the peritoneal cavity duringthe subsequent fill-dwell-drain cycles during a therapy. Preferably, thesubsequent fill volumes are also reduced to match the drain volume(minus the expected UF) in order to maintain a relatively constantresidual intraperitoneal volume. For example, an initial fill volume of3000 ml may be introduced at the beginning of therapy, followed bysubsequent drain and [fill plus expected UF] volumes amounting to only1500 ml, i.e. 50% of the initial fill volume. The reserve or residualfluid in the peritoneal cavity is then drained completely at the end oftherapy. In an alternative mode, a complete drain may be attempted aftera pre-determined or prescribed number of fill-dwell-drain cycles (e.g.,a complete drain may be attempted after three cycles of tidal therapy,this grouping comprising a therapy “cluster”). TPD may be beneficial inthat users may experience less discomfort associated with repeated largefill volumes or repeated attempts to fully empty the peritoneal cavity.Low-flow conditions associated with small intraperitoneal fluid volumesmay also be reduced, thus helping to avoid extending the total therapytime. To reduce the discomfort associated with attempting to drain smallresidual volumes, for example, the tidal drain volume may be set at 75%of the initial fill volume (plus-or-minus expected UF volume), forexample, leaving approximately 25% as a reserve or residual volume inthe peritoneal cavity for the duration of therapy, or for the durationof a cluster of cycles.

A cycler may also be programmed to convert a CCPD mode of therapy to aTPD mode of therapy during the course of therapy if the user chooses tokeep a residual volume of fluid in the peritoneal cavity at the end ofthe subsequent drain phases (e.g., for comfort reasons). In this case,the cycler is programmed to calculate a choice of residual volumes (orvolumes as a percent of initial fill volume) based on the number ofextra cycles to be added to the therapy and the volume of remainingdialysate to be infused. For example, the cycler controller cancalculate the remaining fill volumes based on the remaining cycles thatinclude an additional one, two or more cycles. Having determined thefill volumes for each of these possibilities, the cycler controller cancalculate how much residual volume can be left at the end of eachremaining drain phase while ensuring that the IPV remains under amaximum prescribed IPV (Max IPV). The cycler may then present the userwith a range of possible residual volumes (as a percentage of theinitial fill volume or in volumetric terms) available for each remainingcycle in a therapy extended by one, two or more cycles. The user maymake the selection based on the number of extra cycles chosen and thedesired amount of post-drain residual volume. Switching to tidal therapymay help to reduce the number of low-drain-flow alerts to the user,which can be particularly advantageous during nighttime therapy.

In switching to tidal mode, the cycler may be programmed to select areserve or residual volume percentage (volume remaining in theperitoneal cavity as a percent of the fill volume plus expected UF).Alternatively, the reserve volume may be user-selectable orclinician-selectable from a range of values, optionally with theclinician having the ability to select a wider range of possible valuesthan the user. In an embodiment, the cycler may calculate the effects ofadding one, two or three additional cycles on the remaining fill volumesand the expected residual IP volume percentage, and give the user orclinician the option of selecting among those calculated values.Optionally, the cycler may be constrained to keep the residual IP volumepercentage below a pre-determined maximum value (e.g., a percentage ofthe initial fill volume plus expected UF, or a percentage of the maximumpermissible IPV).

If CCPD is converted to TPD, one or more therapy cycles(fill-dwell-drain cycles) may need to be added to a therapy to use allof the prescribed volume of dialysate for the therapy session. Theremaining volume to be infused going forward would then be divided bythe remaining number of cycles. Furthermore, the cycler may beprogrammed to allow the clinician or user to select between extendingthe targeted total therapy time to accommodate the additional cycles(cycle-based therapy), or to attempt to maintain the targeted therapytime by adjusting the dwell times (i.e., shortening them) if necessaryto reduce the fill-dwell-drain cycle durations going forward (time-basedtherapy).

In an alternative embodiment, the cycler may allow the residual IPvolume to fluctuate (optionally within pre-determined limits) from onecycle to the next, depending on how much fluid can be drained within aspecified drain time interval. The time available for the drain phasemay be limited if the cycler has been programmed to complete the therapywithin the previously scheduled time, or the drain phase may beterminated to prevent the cycler from attempting to pull fluid at a slowrate for a prolonged period of time. In switching from CCPD to TPD, ifthe cycler adds one or more additional cycles to perform a completetherapy with the available dialysate solution, then meeting thescheduled therapy end-time may require shortening the dwell times, orreducing each drain phase, which could cause the residual volume for thetidal mode to vary, depending on the drain flow conditions. As thecycler estimates and tracks the amount of residual volume, it may beprogrammed to calculate whether the subsequent fill volume plus expectedUF volume will reach or exceed a prescribed maximum IPV. If so, thecycler can alert and provide the user with two or more options: the usermay terminate treatment, repeat or extend a drain phase in an attempt tolower the residual intraperitoneal volume, or add a cycle to reduce thesubsequent fill volumes. After calculating the effect on treatment timeof adding an additional one or more cycles (increased number of cyclesvs. reduced fill and drain times at lower volumes) the cycler mayoptionally reduce subsequent dwell times by an amount of time necessaryto offset the additional therapy time generated by an additional one ormore cycles. The cycler may be programmed to deliver an optionallast-fill phase that delivers fresh dialysate of the same or a differentcomposition to the user's peritoneal cavity for an extended dwell timewhile not connected to the cycler (e.g., a prolonged dwell phase for a“day therapy,” i.e., during the day following a nighttime therapy). Atthe user's option, the last fill volume may be selected to be less thanthe fill volumes used during nighttime therapy. The cycler may alsooptionally prompt the user to select an optional extra last drain togive the user the chance to completely empty the peritoneal cavity priorto the infusion of a last fill volume (which may be carried by the userfor a relatively prolonged period of time after the end of nighttimetherapy). If this function is enabled, the cycler may prompt the user tosit up or stand, or otherwise move about to mobilize any trapped fluidin the peritoneal cavity during this last drain phase.

The cycler may also be programmed to account for an expected amount ofultrafiltration (“UF”) fluid produced during a dwell phase on or off themachine, and to alert the user if a minimum drain volume that includesthe volume infused plus this expected UF is not drained either initiallyat the beginning of therapy, or during a fill-dwell-drain cycle duringtherapy. In an embodiment, the cycler may be programmed for a minimuminitial drain volume and a minimum initial drain time, and to pause orterminate the drain phase if the measured drain flow rate has decreasedbelow a pre-determined threshold value for a pre-determined number ofminutes. The minimum initial drain volume may comprise the volume of thelast fill phase in the preceding nighttime therapy, plus an expected UFvolume from the day therapy dwell phase. If the minimum (or more)initial drain volume is achieved, the minimum initial drain time isreached, and/or the drain flow rate has decreased, the IPV tracked bythe cycler controller may be set to zero at the end of the initial drainphase. If not, the cycler may alert the user. The cycler may allow theuser to bypass the minimum initial drain volume requirement. Forexample, the user may have manually drained at some time beforeinitiating APD. If the user elects to forego adherence to the minimuminitial drain volume, the cycler may be programmed to perform a fulldrain at the end of the first cycle regardless of the type of therapyselected by the user. If enabled, this feature helps to ensure that thesecond fill-dwell-drain cycle begins at an IPV that is as close to zeroas possible, helping to ensure that a prescribed maximum IPV should notbe exceeded during subsequent cycles of the therapy.

The cycler may also be programmed to allow the user to pause therapy.During a pause, the user may have the option to alter the therapy byreducing the fill volume, reducing therapy time, terminating a planned“day therapy,” or ending therapy altogether. In addition, the user mayhave the option to perform an immediate drain at any time duringtherapy. The volume of an unscheduled drain may be selected by the user,whereupon the cycler may resume the cycle at the stage at which it wasinterrupted.

The cycler may be programmed to have a prescriber or “clinician” mode. Asoftware application may be enabled to allow a clinician to create ormodify a set of parameters forming the therapy prescription for aparticular patient or user, as well as setting the limits within which auser may adjust user-accessible parameters. The clinician mode may alsoallow a clinician to fix one or more treatment parameters that wouldotherwise be accessible to a user, as well as lock a parameter toprevent a user from changing it. A clinician mode may bepassword-protected to prevent unauthorized access. The clinician modeapplication may be constructed to interface with a database to read andwrite the parameters comprising a prescription. Preferably, a “usermode” permits a user to access and adjust user-accessible parametersduring a pre-therapy startup phase of a therapy. In addition, an “activetherapy mode” may optionally be available to a user during therapy, butwith access to only a subset of the parameters or parameter rangesavailable in the user mode. In an embodiment, the cycler controller maybe programmed to allow parameter changes during active therapy mode toaffect only the current therapy, the parameter settings being reset topreviously prescribed values before subsequent therapies. Certainparameters preferably are not user-adjustable at all, user-adjustablewith concurrence of a clinician through a prescription setting, oruser-adjustable only within a range of values set by a clinician inprogramming a prescription. Examples of parameters that may not beadjustable solely by the user include, for example, the minimum initialdrain volume or time, maximum initial fill volume, and maximum IPV.User-adjustable parameters may include, for example, the tidal drainfrequency in a cluster (e.g., adjustable between 1 and 5 cycles), andthe percentage of a tidal therapy fill volume to be drained (e.g.,adjustable up or down by a pre-determined amount from a default valueof, for example, 85%). In an alternative embodiment, the clinician modemay allow a clinician to prevent a user from programming a maximum IPVto be greater than a pre-determined multiple (e.g., 200%) of the initialfill volume assigned to a nighttime fill-dwell-drain cycle.

The cycler may also be programmed to routinely alert the user and torequest confirmation when a user-adjustable parameter is entered that isoutside of pre-determined ranges. For example, if the maximum IPV hasbeen made user-adjustable in the clinician mode, the cycler may alertthe user if he or she attempts to select a Max IPV value outside of afractional range (e.g., 130-160%) of the programmed fill volume fornighttime therapy.

The cycler may also be programmed to alert the user (and possibly seekconfirmation) if the initial drain volume has been made user-adjustablein the clinician mode, and the user selects an initial drain volumebelow a pre-determined percentage of the fill volume of the last therapy(e.g., if it is adjusted to be less than 70% of the last fill volume).In another example, the cycler may be programmed to alert the user (andpossibly seek confirmation) if the total expected UF volume has beenmade user-adjustable by the clinician mode, and the user selects a totalexpected UF volume to be below a certain percentage of the total volumeprocessed for a nighttime therapy (e.g., if the total expected UF volumeis set at less than 7% of the total nighttime therapy volume). Generallythe expected UF volume may be determined empirically by a clinicianbased on a user's prior experience with peritoneal dialysis. In afurther embodiment, the cycler may be programmed to adjust the expectedUF volume value according to the actual UF volume in one or morepreceding cycles of a therapy. This volume may be calculated in a CCPDmode by calculating the difference between a measured full drain volumeand the measured fill volume that preceded it. In some cases, it may bedifficult to determine when the peritoneal cavity is fully drained offluid, and it may be preferable to take an average value of thedifference between a full drain volume and a preceding fill volume overa number of cycles.

Some of the programmable treatment settings may include:

-   -   the number of daytime exchanges using the cycler;    -   the volume of solution to be used for each daytime exchange;    -   the total time for a nighttime therapy;    -   the total volume of dialysis solution to be used for nighttime        therapy (not including a last fill volume if a daytime dwell        phase is used);    -   the volume of dialysis solution to be infused per cycle;    -   in a Tidal therapy, the volume of fluid to be drained and        refilled during each cycle (a percentage of the initial fill        volume in a nighttime therapy);    -   the estimated ultrafiltration volume to be produced during a        nighttime therapy;    -   the volume of solution to be delivered at the end of a therapy        and to be left in the peritoneal cavity for an extended period        (e.g, daytime dwell);    -   the minimum initial drain volume required to proceed with a        therapy;    -   the maximum intraperitoneal volume known or estimated to be        present that the cycler will allow to reside in the patient's        peritoneal cavity (which may be based on the measured volumes        introduced into the peritoneal cavity, the measured volume        removed from the peritoneal cavity, and the estimated volume of        ultrafiltration produced during therapy).        Some of the more advanced programmable treatment settings for        the cycler may include:    -   the frequency of full drains to be conducted during tidal        peritoneal dialysis;    -   the minimum percentage of the volume delivered to the peritoneum        during a day therapy that must be drained before a subsequent        fill is allowed;    -   prompting the user to perform an extra drain phase at the end of        therapy if a pre-determined percentage of the estimated total UF        is not collected;    -   a minimum length of time required to perform an initial drain        before therapy begins;    -   a minimum length of time required to perform subsequent drains,        either in day-therapy mode or night-therapy mode;    -   variable dwell times, adjusted by the cycler controller to        maintain a fixed total therapy time when either the fill times        or drain times have been changed (thus helping to avoid        disruptions of the user's schedule;        The cycler can provide the user with alerts or warnings about        parameters that have been entered outside a recommended range of        values. For example, a warning may be issued if:    -   the minimum initial drain volume before a therapy is less than a        pre-determined percentage of the currently prescribed last-fill        volume at the end of the previous therapy (e.g., <70%);    -   the maximum IPV is outside a pre-determined percentage range of        the fill volume per cycle (e.g., <130% or >160%);    -   the UF volume threshold to trigger an alert to perform an extra        drain at the end of therapy is less than a pre-determined        percentage of the estimated UF volume per therapy (e.g. <60%);    -   the calculated or entered dwell time is less than a        pre-determined number of minutes (e.g., <30 minutes);    -   the estimated UF volume per therapy is more than a        pre-determined percentage of the total dialysis solution volume        per therapy (e.g., >25%);    -   the sum of all the solution bag volumes for a therapy should be        somewhat greater than the volume of solution used during a CCPD        therapy session, in order to account for priming of fluid lines        and for loss of fluid to drain during air mitigation procedures.

In the clinician mode, in addition to having a selectable maximum IPV,the cycler may be programmed to accept separate minimum drain times forinitial drains, day-therapy drains, and night-therapy drains. In theuser mode or in the active-therapy mode, the cycler may be programmed toprevent a user from skipping or shortening the initial drain phase atthe start of a therapy. In addition, the cycler may permit earlytermination of the initial drain phase only after a series of escalatinglow-drain-flow alerts have been issued. (An initial alert may instructthe user to change positions or re-position the peritoneal dialysiscatheter, which may then be followed by additional alternativeinstructions if low flow conditions persist, up to a maximum number ofalerts). The cycler may also require the user to confirm any change theuser makes to the planned therapy, including bypassing a phase. Theclinician may specify in a prescription setting to prevent the user frombypassing a drain phase during nighttime therapy. During therapy, thecycler controller may be programmed to not reset the IPV to zero unlessthe drain volume exceeds the preceding fill volume (to account for theadditional IPV produced by ultrafiltration). The cycler may also beprogrammed to display to the user the estimated IPV during fills, andmay notify the user if any drain volume exceeds the fill volume by apre-determined amount (e.g. drain volume greater than fill volume plusexpected UF volume). The cycler may also be programmed to identifyerrors in user input and to notify the user of apparent input errors.For example, the number of cycles during a therapy calculated by thecycler, based on the prescription parameters entered by the clinician oruser, should be within a pre-determined range (e.g. 1-10). Similarly,the dwell time calculated by the cycler should be greater than zero. Inaddition, the maximum IPV entered by the user or clinician should begreater than or equal to the fill volume per cycle, plus the expected UFvolume. Furthermore, the cycler may be programmed to reject an enteredvalue for maximum IPV that is greater than a pre-determined amount overthe fill volume per cycle (e.g., maximum IPV <200% of initial fillvolume). In some cases, it may be desirable for the cycler to beprogrammed to set the maximum IPV to no greater than the last fillvolume if the solution is to remain in the peritoneal cavity for aprolonged period of time, such as during a daytime therapy. In thiscase, the cycler may be programmed to alert the user if the cyclercontroller calculates that the last drain volume amounts to less than acomplete drain, whereupon the cycler may provide the user with a choiceto terminate therapy or undertake another drain phase.

Managing Increasing IPV while Minimizing Alarms

In an embodiment, the cycler may be programmed to track and manage anincreasing IPV during a therapy without converting the therapy fromcontinuous cycling peritoneal dialysis (“CCPD”) therapy to a standardtidal peritoneal dialysis (“TPD”) therapy, which would fix the residualvolume to a percentage of the initial fill volume. Rather, an adaptivetidal therapy mode may be initiated, in which the residual volume isallowed to fluctuate or ‘float’ in response to any slow-drain conditionsthat may be encountered during any drain phase. The cycler may beprogrammed to permit this mode to operate as long as any subsequent fillvolume plus expected UF does not exceed a prescribed maximum IPV (“MaxIPV”). Thus the dwell-phase IPV may be permitted to increase or decreaseduring a therapy up to a maximum IPV, preferably set by a clinician inthe clinician mode. In this adaptive tidal therapy mode, at each drainphase during a therapy, the cycler continues to attempt a complete drainwithin the allotted time, or as long as a low-flow or no-flow conditionhas not been detected for a prescribed or pre-set number of minutes. Theresidual volume at the end of the drain phase is allowed to vary or‘float’ as long as it does not exceed an amount that would lead toexceeding the maximum IPV in the next fill phase or during the nextdwell phase. In a preferred embodiment, the cycler may be programmed tonot issue an alert or alarm to the user as long as it calculates thatthe subsequent fill phase or dwell phase will not reach or exceedmaximum IPV.

The cycler may be programmed to deliver full fill volumes during eachcycle of a therapy until the cycler controller calculates that the nextfill volume will likely cause the IPV to exceed the maximum IPV. At aconvenient time (such as, e.g., the end of a drain phase), the cyclercontroller may be programmed to calculate a maximum residual IP volume,which represents the maximum permissible residual IP volume at the endof a drain to allow the next cycle to proceed with the previouslyprogrammed fill volume. Partial drains will be permitted by the cyclerwithout alarming or issuing an alert as long as the amount of fluiddrained brings the residual IPV below the maximum residual IPV. If theestimated or predicted IPV at the end of a drain phase is less than themaximum residual IPV, the cycler can proceed with a full fill phase inthe next cycle without risking exceeding the Max IPV. If the estimatedIPV at the end of a drain is greater than the maximum residual IPV, thecycler controller may trigger an alert to the user that the subsequentfill plus UF may exceed the maximum IPV. In an embodiment, the cyclermay display several options for the user to respond to this alert: itmay allow the user to terminate therapy, to attempt another drain phase,or to proceed to enter a revised-cycle therapy mode, in which eachsubsequent fill volume is reduced and one or more cycles are added tothe therapy (thereby ensuring that the remaining volume of freshdialysate is used during that therapy). In an embodiment, a clinician oruser may enable the cycler at the beginning of therapy to automaticallyenter this revised-cycle therapy mode without having to alert the userduring therapy.

In some circumstances, the number of additional cycles may be limited bythe planned total therapy time. For example, the duration of night timetherapy may be limited by the time at which the user is scheduled towake up or to get up to go to work. For nighttime therapy, the cyclercontroller may be programmed, for example, to prioritize the use of alldialysate solution that was planned for therapy in favor of endingtherapy at the scheduled time. If the clinician or user has selected thedwell time to be adjustable, then the cycler controller will (1) add oneor more cycles to ensure that the fill volume plus expected UF does notexceed maximum IPV; (2) ensure that all of the dialysis solution is usedfor therapy; and (3) attempt to reach the targeted end-of-therapy timeby shortening the dwell times of the remaining cycles. An alternativeoption available to the user is to extend the end-of-therapy time. In apreferred embodiment, the cycler is programmed to add one or twoadditional cycles to the therapy to permit a reduced fill volume inorder to prevent exceeding the maximum IPV. The cycler controller isprogrammed to recalculate the maximum residual IPV using the reducedfill volume occasioned by the increased number of cycles. Thus, if a lowflow condition during drain occurs at the same IPV, the new highermaximum residual IPV may permit dialysis to proceed without exceedingmaximum IPV. If the fill volume cannot be reduced enough by adding amaximum allowable number of extra cycles (e.g., 2 cycles in an exemplarynight time therapy scenario), then the cycler may present the user withtwo options: re-attempt a drain phase, or end therapy. The cycler may beprogrammed to reset the fill volume again after an adjustment of thefill volume, possibly adding an additional cycle, if a low flowcondition at the end of drain is again encountered at an IPV above thenewly recalculated and reset maximum residual IPV. Thus the cycler maybe programmed to repeatedly adjust the subsequent fill volumes toprevent exceeding maximum IPV if a premature low flow condition isrepeatedly encountered.

Replenishment Limitation on Dwell Time Reductions

In an embodiment, if the cycler reduces fill volumes by adding one ormore cycles, then it may also reduce the dwell time in order to attemptto keep the therapy session within the total scheduled therapy time.This mode may be useful for nighttime therapy, so that the patient maybe reasonably assured that therapy will have ended before a planned timeof awakening in the morning. However, the cycler will continue toreplenish the heater bag as needed during therapy, the replenishmentgenerally occurring during dwell phases (when the PD cassette is nototherwise pumping to or from the patient). Therefore, in somecircumstances, total therapy time may need to be extended when therequired reduction in remaining dwell times leads to a total remainingdwell time that is less than the total estimated time needed toreplenish the heater bag with the remaining fresh dialysate. The cyclercontroller may therefore calculate a maximum dwell time reductionavailable for the remaining therapy cycles, and extend total therapytime to ensure that the remaining fresh dialysate is properly heated.Because the cycler controller keeps track of the volume of dialysate inthe heater bag, the temperature of the dialysate in the heater bag, andthe volume of remaining fresh dialysate that is scheduled to be infused,it can calculate an estimate of the amount of time needed to replenishthe heater bag to a pre-determined volume (given its intrinsic pumpingcapacity), and the time needed to bring the dialysate in the heater bagup to the prescribed temperature before it is infused into the user. Inan alternative embodiment, the cycler controller may interrupt pumpingoperations to or from the user at any time in order to engage the pumpsfor replenishment of the heater bag. The cycler controller may beprogrammed, for example, to prevent the volume of fluid in the heaterbag from dropping below a pre-determined volume at any time duringtherapy, other than during the last cycle.

In an embodiment, the cycler may be programmed to deliver fluid to theheater bag at a greater flow rate than when it is transferring fluid toor from the user. If binary valves are used to regulate the flow ofcontrol fluid or gas between the positive/negative pressure reservoirsand the control or actuation chambers of the cassette pumps, thecontroller may issue on-off commands to the valves at different pressurelevels measured in the control or actuation chambers of the pumps. Thusthe pressure threshold in the pump control or actuation chamber at whichthe controller triggers an ‘off’ command to the binary valve may have anabsolute value that is greater during delivery to or from the heater bagthan the corresponding pressure threshold when the cycler is deliveringor pulling fluid to or from the user's peritoneal cavity. A higheraverage pressure applied to the pump membrane may be expected to resultin a greater flow rate of the liquid being pumped. A similar approachmay be used if variable orifice valves are used to regulate the flow ofcontrol fluid or gas between the pressure reservoirs and the control oractuation chambers of the cassette pumps. In this case, the controllermay modulate the flow resistance offered by the variable orifice valvesto maintain a desired pressure in the pump control chamber withinpre-determined limits as the pump membrane is moving through its stroke.

Exemplary Modes of Therapy

FIG. 67 is a graphical illustration (not to scale in either volumes ortime) of an adaptive tidal mode of the cycler when in a CCPD mode. Theinitial drain at the beginning of therapy is omitted for clarity. Themaximum IPV (Max IPV) 700 is a prescription parameter preferably set bythe clinician. The initial fill volume 702 is also preferably set by theclinician as a prescription parameter. The expected UF volume isrepresented by the additional IPV increase 704 during the dwell phase706. The expected UF volume for an entire therapy may be entered by aclinician into the prescription, and the cycler may then calculate thedwell time per cycle based on the number of cycles during the therapy,and thus the expected UF volume per cycle. It should be noted thatultrafiltration is expected to occur throughout the fill-dwell-draincycle, and the expected UF volume may include the volume of fluidultrafiltered throughout the cycle period. In most cases, the dwell timeis much larger than the fill or drain times, rendering theultrafiltration volumes during fill or drain relatively insignificant.(The fill and drain times may be adjustable by altering the pressure setpoints used by the controller to regulate the control valves between thepressure reservoirs and the pumps. However, the adjustability of liquiddelivery flow rates and pressures to the user is preferably limited inorder to ensure user comfort). Thus the expected UF volume per cycle 704may be reasonably representative of ultrafiltration during the cycle.The drain phase 708 of the cycle in this example is a full drain, aswould occur in a CCPD mode of therapy.

The maximum residual volume 710 can be calculated by the cyclercontroller once the Max IPV 700, the initial fill volume 702, and theexpected UF volume are entered by the clinician. The maximum residualvolume 710 is an indication of the ‘headroom’ 712 available in theperitoneal cavity to accommodate more fluid before reaching Max IPV 700.In an adaptive tidal mode within a CCPD mode of therapy, as long as adrain volume 714, 716 leaves an estimated residual volume 718, 720 lessthan the maximum residual volume 710, the subsequent fill volume 722,724 can remain unchanged, because Max IPV 700 is not expected to bebreached. As shown in FIG. 67, the occurrence of a low flow condition atthe residual volumes 718 and 720 triggers the cycler to initiate thenext fill phase 722 and 724. During this form of therapy, the cyclerwill continue to attempt to perform a full drain 726 within an allottedtime assuming a low-flow or no-flow condition is not encountered beforethe estimated zero IPV is reached. Thus, even if a full drain is notperformed (because of a low-flow or no-flow condition), in this case,full fill volumes will continue to be infused, the residual IPV will beallowed to float within a pre-determined range, and the user preferablywill not be disturbed by any alarms or alert notifications.

FIG. 68 is a graphical illustration of how the cycler may handleincomplete drains that fail to reach the maximum residual IPV 710. Inthis case, the drain phase 730 of the third cycle encounters a low-flowor no-flow condition that prevents the cycler from draining theperitoneal cavity below the maximum residual IPV 710. Given theestimated residual volume 732 (the estimated residual volume after apre-determined duration of a low-flow condition), the cycler calculatesthat a subsequent fill phase volume 734 will likely cause the prescribedMax IPV 700 to be reached or exceeded 736. Therefore, at the end ofdrain phase 730, the cycler may alert the user to this issue. The usermay then have the option to terminate therapy, instruct the cycler tore-attempt a drain phase (after possibly changing positions orrepositioning the PD catheter), or instruct the cycler to enter into arevised-cycle therapy mode in which the subsequent fill volumes arereduced and one or more cycles added to complete the therapy with theplanned total volume of dialysate. To keep within the allotted orprescribed total therapy time, the cycler can calculate the duration ofthe modified cycles by reducing the fill and drain times to account forthe reduced fill and drain volumes, and then determining whether and howmuch the dwell times need to be reduced to meet the designated endingtime of the therapy session.

A user may optionally enable a revised-cycle mode of CCPD at thebeginning of a therapy, so that the occurrence of a low-flow conditionduring therapy can trigger the revised-cycle mode without disturbing theuser with an alert or alarm. Otherwise, the user may select therevised-cycle mode upon the occurrence of a low-flow condition above themaximum residual IPV. If the user elects to enter a revised-cycle mode,the cycler controller may calculate the required fill volumes for eachof an additional one, two or more cycles (remaining fill volume dividedby the remaining planned cycles plus the additional one or more cycles).If one additional cycle yields a fill volume (plus expected UF) lowenough to avoid reaching or exceeding Max IPV, the cycler (eitherautomatically or at the user's option) will resume CCPD at that new fillvolume 738. Otherwise, the cycler controller will calculate a new fillvolume based on an additional two cycles of therapy. (Rarely, more thantwo additional cycles may be required to ensure that Max IPV is notbreached during the remaining therapy. If the additional cycles requirea substantial reduction in the remaining dwell times, the cycler mayalert the user, particularly if a minimum dwell time has beenprescribed, or heater bag replenishment limitations will require alengthening of the total therapy time). The now-reduced fill volume 738allows the cycler controller to re-calculate a revised maximum residualIPV 740, which is a function of the sum of the new fill volume plus theexpected UF volume per cycle. Any subsequent drain phases that leave anestimated residual IP volume less than the revised maximum residualvolume 740 will preferably not trigger any further alerts or alarms tothe user, allowing for the adaptive mode of tidal therapy to remainenabled. In an embodiment, the cycler may re-calculate the expected UFvolume if it has reduced the duration of the remaining dwell phases inorder to stay within the planned total therapy time. Any re-calculatedreduction in the expected UF volume may further increase the revisedmaximum residual IPV. In the example shown in FIG. 68, the cyclercontinues to perform CCPD mode therapy, and happens to be able to drainfully in the remaining cycles. In order not to further inconvenience theuser, the cycler may optionally refrain from making any furtheradjustments to the therapy (particularly if the total volume ofdialysate and the total therapy time have been kept within theprescribed parameters).

FIG. 69 illustrates that a planned standard tidal peritoneal dialysis(TPD) therapy may also be subject to a revised-cycle mode of TPD therapyif the cycler controller calculates that the user's Max IPV 700 islikely to be reached or exceeded during therapy. In this example, a useror clinician has selected a standard tidal therapy, in which a plannedresidual IP volume 742 (in actual volumetric terms or as a percentage ofthe initial fill volume) has been selected. As an optional feature ofthe cycler, the user or clinician has also chosen to perform a completedrain 744 after every three tidal fill-dwell-drain cycles, comprising acycle cluster during a therapy session. In this example, a low-flowcondition preventing draining below the maximum residual volume 710occurs at the end of the third cycle 746. At the option of the user orclinician, the cycler either alerts the user to choose to end therapy,repeat a drain phase, or initiate a revised-cycle TPD therapy, or thecycler is allowed to automatically initiate a revised-cycle TPD therapy.In this case, the addition of a sixth cycle with a consequent reductionof the fill volume to a revised fill volume 748, is sufficient to avoidexceeding the Max IPV 700, which otherwise would have occurred 750. Inthis example, the cycler proceeds to perform a complete drain 744 at theend of a cluster, but resumes a standard TPD therapy thereafter. If theplanned residual volume has been specified to be a percentage of theinitial fill volume of the cluster, then that percentage may be appliedto a revised residual IPV 752. The cycler may then calculate thesubsequent drain volumes 754 by calculating the appropriate fraction ofthe revised fill volume 748 plus expected UF volume in order to drain tothe revised residual IPV 752. Any subsequent fill volumes 758 may remainsimilar to the revised fill volume 748, as long as the cycler calculatesthat the Max IPV 700 will not be breached. Alternatively, the subsequentfill volumes may be reduced in a manner designed to maintain arelatively constant revised dwell-phase IPV 756. In this case, thecycler controller may be programmed to make the additional calculationsnecessary to ensure that the entire remaining dialysate solution will beproperly divided among a revised fill volume 748 and later fill volumesreduced to maintain a revised dwell-phase IPV 756. In an alternativeembodiment, the clinician or user may select the prescribed residual IPvolume 742 to be relatively fixed volumetrically throughout therapy. Inthis case, the cycler controller may convert the percentage value of theresidual IP volume 742 into a volumetric value (e.g. in milliliters),and continue to use that targeted residual volume after therevised-cycle mode has been instituted. In any event, the cyclercontroller may continue to apply the Max IPV 700 limitation incalculating any revised fill volumes.

FIG. 70 illustrates how an adaptive tidal therapy mode may be employedduring a standard tidal therapy. In this example, a slow-drain condition760 is encountered below the maximum residual volume 710. As an optionalfeature of the cycler, the user or clinician has also chosen in thisexample to perform a complete drain 764 after every four tidalfill-dwell-drain cycles, comprising a cycle cluster during a therapysession. In this case, the cycler calculates that the Max IPV 700 willnot be reached if the tidal fill volume 762 is maintained. The cyclermay be programmed to continue the tidal therapy at a revised residual IPvolume 760 in order to avoid another slow-drain condition.(Alternatively, the cycler may be programmed to attempt to drain back tothe previously prescribed residual IP volume 742). Since tidal therapycan continue without risk of breaching Max IPV 700, the user need not bealerted to the institution of a revised or floating residual volume ofthe adaptive tidal therapy mode. A full drain 764 is initiated asprescribed, and if successful, the cycler controller may re-institutethe originally prescribed tidal therapy parameters. In an embodiment,the cycler may be programmed to alert the user if a full drain cannot beachieved at the end of a tidal therapy cluster.

While aspects of the invention have been described in conjunction withspecific embodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart. Accordingly, embodiments of the invention as set forth herein areintended to be illustrative, not limiting. Various changes may be madewithout departing from the spirit and scope of the invention.

1-13. (canceled)
 14. A method for performing peritoneal dialysis using apre-determined total volume of dialysate and comprising a plurality oftherapy cycles, each cycle comprising infusing dialysate into aperitoneal cavity, allowing dialysate to dwell in the peritoneal cavityfor a period of time, and draining dialysate from the peritoneal cavity,the method comprising: selecting a value for a maximum volume ofdialysate that may reside in the peritoneal cavity; selecting a valuefor a first infusion volume of dialysate to be infused into theperitoneal cavity; estimating a volume of ultrafiltration fluid producedin the peritoneal cavity during a therapy cycle; measuring the volume ofdialysate infused in the peritoneal cavity during a cycle; measuring thevolume of dialysate drained from the peritoneal cavity during the cycle;estimating a volume of residual dialysate remaining in the peritonealcavity; and initiating a new therapy cycle before the total of theinfused volume plus the estimated ultrafiltered volume of fluid havebeen drained as long as an estimated residual volume of dialysate in theperitoneal cavity plus the amount of the infused volume plus theestimated ultrafiltered volume in the new therapy cycle does not exceedthe maximum volume of dialysate that may reside in the peritonealcavity. 15-17. (canceled)
 18. A peritoneal dialysis system forperforming peritoneal dialysis using a pre-determined total volume ofdialysate and arranged to employ a plurality of therapy cyclescomprising a fill phase in which dialysate is delivered from thedialysis system via a patient line, a dwell phase, and a drain phase inwhich fluid is drained via a drain line, the system comprising: at leastone pump chamber controllable to move fluid; a patient line in fluidcommunication with the at least one pump chamber to receive dialysatefrom the at least one pump chamber for delivery; a drain line in fluidcommunication with the at least one pump chamber to deliver fluid to theat least one pump chamber; a plurality of valves to selectively controlflow in flow channels of the dialysis system; and a control systemarranged to control the dialysis system to perform the following:control the at least one pump chamber and the plurality of valves todeliver a first infusion volume of dialysate to the patient line as partof a therapy cycle; measure a volume of dialysate delivered to thepatient line during the therapy cycle; control the at least one pumpchamber and the plurality of valves to receive fluid from the drain lineas part of the therapy cycle; measure a volume of fluid received fromthe drain line during the therapy cycle; estimate a volume ofultrafiltration fluid produced during the therapy cycle; estimate avolume of residual fluid for the therapy cycle based on the measuredvolume of fluid received, the estimated ultrafiltration fluid producedand the measured volume of dialysate delivered; determine a value for amaximum volume of fluid at the end of a dwell phase; and initiate a nexttherapy cycle if the estimated residual volume of fluid for the cycleplus a volume of dialysate to be delivered for the next therapy cycleplus an estimated volume of ultrafiltration fluid produced for the nexttherapy cycle does not exceed the maximum volume of fluid at the end ofa dwell phase.
 19. A system for controlling a temperature of a solutionline connector having a pierceable seal through which a hollow spike maybe connected, comprising: a carriage on which the connector is placed; asensor mounted on the carriage to detect the temperature of theconnector; a heating or cooling element positioned near the connector toaffect the temperature of the connector; and a controller to receivetemperature data from the sensor and to control the heating or coolingelement.
 20. (canceled)
 21. A gasket for transferring positive ornegative pressure from a peritoneal dialysis apparatus to a pumpingcassette, the cassette having a generally planar body and a firstflexible membrane covering one or more pump or valve chambers on thecassette, the gasket comprising: one or more control regions, eachcomprising a second flexible membrane arranged to align with one or morepumping or valve chambers on the pumping cassette, the pumping or valvechambers each bounded by at least a portion of the first flexiblemembrane, each said portion of the first flexible membrane arranged tomake direct contact with an opposing control region; a perimeter regionarranged to fit the gasket securely over a pressure delivery block ofthe peritoneal dialysis apparatus, the pressure delivery blockconfigured to channel positive or negative pressure to the one or morecontrol regions; wherein a surface of each of the control regions facingthe first flexible membrane is roughened or textured to form a porouslayer of the surface of the control region when placed in contact withthe first flexible membrane.
 22. A disposable component system for usewith a fluid line connection system of a peritoneal dialysis system, thedisposable component system comprising: a fluid handling cassettecomprising: a generally planar body with at least one pump chamberformed as a depression in a first side of the body and a plurality offlowpaths for fluid; a solution line spike located at a first end of thebody, the solution line spike being in fluid communication with the atleast one pump chamber via at least one flowpath; and a spike capconfigured to removably cover the solution line spike, wherein the capincludes at least a flange on an outer surface of the spike cap to aidin removal of the cap from the spike for connection of the spike to asolution line, and a barb on the outer surface of the spike capconfigured to engage the spike cap with a hole of a solution line cap.23-26. (canceled)
 27. A pressure distribution module for a fluid flowcontrol apparatus configured to operate a membrane-based pumpingcassette, the module comprising: a manifold comprising an inlet port forpositive pressure and an inlet port for negative pressure, and aplurality of channels and valves arranged to selectively connect asource of positive or negative pressure to a plurality of outletchannels; a pressure delivery block configured to mate with a side ofthe manifold, wherein a plurality of outlet channels of the manifoldfluidly connect with opposing ports on a first side of the pressuredelivery block, the opposing ports on the first side of the pressuredelivery block fluidly connected to corresponding outlet ports on anopposing second side of the pressure delivery block; and a controlgasket mounted on the second side of the pressure delivery block andhaving a plurality of control regions, each control region having afirst side positioned opposite an outlet port of the pressure deliveryblock, and each control region having an opposing second side configuredto contact and actuate a pumping or valve membrane of a pumpingcassette; wherein each control region may be positively or negativelypressurized through a corresponding outlet port of the pressure deliveryblock. 28-47. (canceled)
 48. A control system for a medical fluiddelivery apparatus comprising: a pumping apparatus configured to pumpfluid to a patient from one or more source containers of fluid, or froma patient to a receptacle, the apparatus comprising one or more pumps,one or more valves, and fluid connections among the pumps, valves andthe source containers or receptacle of fluid; one or more pressuresensors to detect pumping pressures of the one or more pumps; a firstprocessor configured to control a sequence and timing of valve and pumpoperations to implement a pumping of fluid from one or more sourcecontainers to the patient or from the patient to the receptacle, andconfigured to monitor one or more volumes of fluid being pumped; and asecond processor configured to implement commands of the first processorand to provide data to the first processor, wherein the second processoris configured to: collect and store data received from the pressuresensors at pre-determined fixed rate; provide the stored data to thefirst processor on command from the first processor; control the pumpingpressure of the one or more pumps on a pre-determined fixed schedule;and to open or close the valves on command from the first processor. 49.A power management system for a medical device while operating onbattery power comprising: a medical device having a plurality offunctions, each function associated with one of a pre-determined numberof levels of power consumption; an electronic circuit configured tomeasure an amount of charge remaining in a battery powering the medicaldevice, and to associate the amount of charge with one of thepre-determined levels of power consumption; and a controller configuredto allow the medical device to perform one or more functions of theplurality of functions, as long as the one or more functions and themeasured amount of charge are associated with the same level of powerconsumption.